I discovered that Flow's Flow\Tests\Block\TopicListBlockTest::testSortByOption fails and makes merges to (at least) GrowthExperiments impossible:
11:49:38 1) Flow\Tests\Block\TopicListBlockTest::testSortByOption
11:49:38 Default sortby now changed to updated
11:49:38 Failed asserting that two strings are equal.
11:49:38 --- Expected
11:49:38 +++ Actual
11:49:38 @@ @@
11:49:38 -'updated'
11:49:38 +'newest'
11:49:38
11:49:38 /workspace/src/extensions/Flow/tests/phpunit/integration/Block/TopicListBlockTest.php:68
11:49:38 /workspace/src/tests/phpunit/MediaWikiIntegrationTestCase.php:547
11:49:38 phpvfscomposer:///workspace/src/vendor/phpunit/phpunit/phpunit:97
11:49:38 === Logs generated by test case
11:49:38 [objectcache] [debug] MainWANObjectCache using store {class} {"class":"HashBagOStuff"}
11:49:38 [localisation] [debug] LocalisationCache using store LCStoreNull []
11:49:38 [localisation] [debug] LocalisationCache::isExpired(en): cache missing, need to make one []
11:49:38 [objectcache] [debug] MainObjectStash using store {class} {"class":"HashBagOStuff"}
11:49:38 ===see https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GrowthExperiments/+/946926 (test pipeline) or https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GrowthExperiments/+/942371 (gate-and-test pipeline).