diff --git a/Documentation/user-search.txt b/Documentation/user-search.txt
index 44921ad..4293fd6 100644
--- a/Documentation/user-search.txt
+++ b/Documentation/user-search.txt
@@ -377,6 +377,10 @@
 The link:http://www.brics.dk/automaton/[dk.brics.automaton library,role=external,window=_blank]
 is used for the evaluation of such patterns.
 +
+Note that the Gerrit host may not support regular expression search.
+You will then see an error dialog when using expressions starting with
+`^`.
++
 The `^` required at the beginning of the regular expression not only
 denotes a regular expression, but it also has the usual meaning of
 anchoring the match to the start of the string.  To match all Java
diff --git a/java/com/google/gerrit/server/query/change/MagicLabelPredicates.java b/java/com/google/gerrit/server/query/change/MagicLabelPredicates.java
index 82d8717..9ee4852 100644
--- a/java/com/google/gerrit/server/query/change/MagicLabelPredicates.java
+++ b/java/com/google/gerrit/server/query/change/MagicLabelPredicates.java
@@ -16,6 +16,7 @@
 
 import static com.google.gerrit.server.query.change.EqualsLabelPredicates.type;
 
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.entities.Account;
 import com.google.gerrit.entities.Change;
@@ -30,6 +31,8 @@
 import java.util.Optional;
 
 public class MagicLabelPredicates {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
   public static class PostFilterMagicLabelPredicate extends PostFilterPredicate<ChangeData> {
     private static class PostFilterMatcher extends Matcher {
       public PostFilterMatcher(
@@ -177,6 +180,7 @@
     }
 
     public boolean ignoresUploaderApprovals() {
+      logger.atFine().log("account = %d", account.get());
       return account.equals(ChangeQueryBuilder.NON_UPLOADER_ACCOUNT_ID)
           || account.equals(ChangeQueryBuilder.NON_CONTRIBUTOR_ACCOUNT_ID);
     }
diff --git a/java/com/google/gerrit/server/submit/MergeMetrics.java b/java/com/google/gerrit/server/submit/MergeMetrics.java
index e9832fd..4c7a197 100644
--- a/java/com/google/gerrit/server/submit/MergeMetrics.java
+++ b/java/com/google/gerrit/server/submit/MergeMetrics.java
@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.submit;
 
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.entities.SubmitRequirement;
 import com.google.gerrit.index.query.Predicate;
 import com.google.gerrit.index.query.QueryParseException;
@@ -28,6 +29,8 @@
 
 /** Metrics are recorded when a change is merged (aka submitted). */
 public class MergeMetrics {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
   private final Provider<SubmitRequirementChangeQueryBuilder> submitRequirementChangequeryBuilder;
 
   // TODO: This metric is for measuring the impact of allowing users to rebase changes on behalf of
@@ -81,12 +84,19 @@
     // impersonated. Impersonating the uploader is only allowed on rebase by rebasing on behalf of
     // the uploader. Hence if the current patch set has different accounts as uploader and real
     // uploader we can assume that it was created by rebase on behalf of the uploader.
-    return !cd.currentPatchSet().uploader().equals(cd.currentPatchSet().realUploader());
+    boolean isRebaseOnBehalfOfUploader =
+        !cd.currentPatchSet().uploader().equals(cd.currentPatchSet().realUploader());
+    logger.atFine().log("isRebaseOnBehalfOfUploader = %s", isRebaseOnBehalfOfUploader);
+    return isRebaseOnBehalfOfUploader;
   }
 
   private boolean hasCodeReviewApprovalOfRealUploader(ChangeData cd) {
-    return cd.currentApprovals().stream()
-        .anyMatch(psa -> psa.accountId().equals(cd.currentPatchSet().realUploader()));
+    boolean hasCodeReviewApprovalOfRealUploader =
+        cd.currentApprovals().stream()
+            .anyMatch(psa -> psa.accountId().equals(cd.currentPatchSet().realUploader()));
+    logger.atFine().log(
+        "hasCodeReviewApprovalOfRealUploader = %s", hasCodeReviewApprovalOfRealUploader);
+    return hasCodeReviewApprovalOfRealUploader;
   }
 
   private boolean ignoresCodeReviewApprovalsOfUploader(ChangeData cd) {
@@ -105,6 +115,9 @@
   }
 
   private boolean ignoresCodeReviewApprovalsOfUploader(Predicate<ChangeData> predicate) {
+    logger.atFine().log(
+        "predicate = (%s) %s (child count = %d)",
+        predicate.getClass().getName(), predicate, predicate.getChildCount());
     if (predicate.getChildCount() == 0) {
       // Submit requirements may require a Code-Review approval but ignore approvals by the
       // uploader. This is done by using a label predicate with 'user=non_uploader' or
diff --git a/plugins/package.json b/plugins/package.json
index 2299a93..612062b 100644
--- a/plugins/package.json
+++ b/plugins/package.json
@@ -32,7 +32,7 @@
     "@codemirror/theme-one-dark": "^6.1.1",
     "@codemirror/view": "^6.9.1",
     "lit": "^2.2.3",
-    "rxjs": "^7.8.0",
+    "rxjs": "^6.6.7",
     "sinon": "^13.0.0"
   },
   "license": "Apache-2.0",
diff --git a/plugins/yarn.lock b/plugins/yarn.lock
index bad5fcc..3156f4c 100644
--- a/plugins/yarn.lock
+++ b/plugins/yarn.lock
@@ -2480,12 +2480,12 @@
   dependencies:
     queue-microtask "^1.2.2"
 
-rxjs@^7.8.0:
-  version "7.8.0"
-  resolved "https://registry.yarnpkg.com/rxjs/-/rxjs-7.8.0.tgz#90a938862a82888ff4c7359811a595e14e1e09a4"
-  integrity sha512-F2+gxDshqmIub1KdvZkaEfGDwLNpPvk9Fs6LD/MyQxNgMds/WH9OdDDXOmxUZpME+iSK3rQCctkL0DYyytUqMg==
+rxjs@^6.6.7:
+  version "6.6.7"
+  resolved "https://registry.yarnpkg.com/rxjs/-/rxjs-6.6.7.tgz#90ac018acabf491bf65044235d5863c4dab804c9"
+  integrity sha512-hTdwr+7yYNIT5n4AMYp85KA6yw2Va0FLa3Rguvbpa4W3I5xynaBZo41cM3XM+4Q6fRMj3sBYIR1VAmZMXYJvRQ==
   dependencies:
-    tslib "^2.1.0"
+    tslib "^1.9.0"
 
 safe-buffer@5.2.1, safe-buffer@~5.2.0:
   version "5.2.1"
@@ -2681,10 +2681,10 @@
   resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"
   integrity sha512-N3WMsuqV66lT30CrXNbEjx4GEwlow3v6rr4mCcv6prnfwhS01rkgyFdjPNBYd9br7LpXV1+Emh01fHnq2Gdgrw==
 
-tslib@^2.1.0:
-  version "2.5.0"
-  resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.5.0.tgz#42bfed86f5787aeb41d031866c8f402429e0fddf"
-  integrity sha512-336iVw3rtn2BUK7ORdIAHTyxHGRIHVReokCR3XjbckJMK7ms8FysBfhLR8IXnAgy7T0PTPNBWKiH514FOW/WSg==
+tslib@^1.9.0:
+  version "1.14.1"
+  resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.14.1.tgz#cf2d38bdc34a134bcaf1091c41f6619e2f672d00"
+  integrity sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==
 
 tsscmp@1.0.6:
   version "1.0.6"
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
index c38e788..de6a39c9 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
@@ -237,7 +237,7 @@
    * This is triggered when the user types into the editing textarea. We then
    * debounce it and call autoSave().
    */
-  private autoSaveTrigger$ = new Subject<void>();
+  private autoSaveTrigger$ = new Subject();
 
   /**
    * Set to the content of DraftInfo when entering editing mode.
diff --git a/polygerrit-ui/app/models/checks/checks-model_test.ts b/polygerrit-ui/app/models/checks/checks-model_test.ts
index 35a8465..da4e3f1 100644
--- a/polygerrit-ui/app/models/checks/checks-model_test.ts
+++ b/polygerrit-ui/app/models/checks/checks-model_test.ts
@@ -139,9 +139,6 @@
     // emits at 'trailing' of throttle interval
     assert.equal(fetchSpy.callCount, 1);
 
-    // 600 ms is greater than the 500 ms throttle time.
-    clock.tick(600);
-
     model.reload('test-plugin');
     model.reload('test-plugin');
     model.reload('test-plugin');
diff --git a/polygerrit-ui/app/package.json b/polygerrit-ui/app/package.json
index 32aff91..edf0206 100644
--- a/polygerrit-ui/app/package.json
+++ b/polygerrit-ui/app/package.json
@@ -42,7 +42,7 @@
     "polymer-bridges": "file:../../polymer-bridges/",
     "polymer-resin": "^2.0.1",
     "resemblejs": "^4.0.0",
-    "rxjs": "^7.8.0",
+    "rxjs": "^6.6.7",
     "safevalues": "^0.3.1",
     "web-vitals": "^3.0.0"
   },
diff --git a/polygerrit-ui/app/yarn.lock b/polygerrit-ui/app/yarn.lock
index c021046..e056a35 100644
--- a/polygerrit-ui/app/yarn.lock
+++ b/polygerrit-ui/app/yarn.lock
@@ -846,12 +846,12 @@
   dependencies:
     glob "^7.1.3"
 
-rxjs@^7.8.0:
-  version "7.8.0"
-  resolved "https://registry.yarnpkg.com/rxjs/-/rxjs-7.8.0.tgz#90a938862a82888ff4c7359811a595e14e1e09a4"
-  integrity sha512-F2+gxDshqmIub1KdvZkaEfGDwLNpPvk9Fs6LD/MyQxNgMds/WH9OdDDXOmxUZpME+iSK3rQCctkL0DYyytUqMg==
+rxjs@^6.6.7:
+  version "6.6.7"
+  resolved "https://registry.yarnpkg.com/rxjs/-/rxjs-6.6.7.tgz#90ac018acabf491bf65044235d5863c4dab804c9"
+  integrity sha512-hTdwr+7yYNIT5n4AMYp85KA6yw2Va0FLa3Rguvbpa4W3I5xynaBZo41cM3XM+4Q6fRMj3sBYIR1VAmZMXYJvRQ==
   dependencies:
-    tslib "^2.1.0"
+    tslib "^1.9.0"
 
 safe-buffer@~5.1.0, safe-buffer@~5.1.1:
   version "5.1.2"
@@ -954,10 +954,10 @@
   resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"
   integrity sha1-gYT9NH2snNwYWZLzpmIuFLnZq2o=
 
-tslib@^2.1.0:
-  version "2.5.0"
-  resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.5.0.tgz#42bfed86f5787aeb41d031866c8f402429e0fddf"
-  integrity sha512-336iVw3rtn2BUK7ORdIAHTyxHGRIHVReokCR3XjbckJMK7ms8FysBfhLR8IXnAgy7T0PTPNBWKiH514FOW/WSg==
+tslib@^1.9.0:
+  version "1.14.1"
+  resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.14.1.tgz#cf2d38bdc34a134bcaf1091c41f6619e2f672d00"
+  integrity sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==
 
 util-deprecate@~1.0.1:
   version "1.0.2"