See for example https://integration.wikimedia.org/ci/job/quibble-vendor-mysql-php74-noselenium-docker/113602/console:
There was 1 error: 1) Error The data provider specified for ApiStructureTest::testParameters is invalid. Wikimedia\Rdbms\DBQueryError: Error 1044: Access denied for user 'wikiuser'@'localhost' to database 'centralauth' Function: Wikimedia\Rdbms\DatabaseMysqlBase::doSelectDomain Query: USE `centralauth` /workspace/src/includes/libs/rdbms/database/Database.php:1300 /workspace/src/includes/libs/rdbms/database/Database.php:1284 /workspace/src/includes/libs/rdbms/database/Database.php:1258 /workspace/src/includes/libs/rdbms/database/DatabaseMysqlBase.php:201 /workspace/src/includes/libs/rdbms/database/Database.php:1589 /workspace/src/includes/libs/rdbms/loadbalancer/LoadBalancer.php:975 /workspace/src/includes/libs/rdbms/loadbalancer/LoadBalancer.php:848 /workspace/src/includes/libs/rdbms/loadbalancer/LoadBalancer.php:840 /workspace/src/includes/libs/rdbms/database/DBConnRef.php:103 /workspace/src/includes/libs/rdbms/database/DBConnRef.php:117 /workspace/src/includes/libs/rdbms/database/DBConnRef.php:334 /workspace/src/includes/libs/rdbms/querybuilder/SelectQueryBuilder.php:726 /workspace/src/extensions/CentralAuth/includes/GlobalGroup/GlobalGroupLookup.php:57 /workspace/src/extensions/CentralAuth/includes/Api/ApiQueryGlobalAllUsers.php:273 /workspace/src/includes/api/ApiBase.php:1831 /workspace/src/tests/phpunit/structure/ApiStructureTest.php:171 phpvfscomposer:///workspace/src/vendor/phpunit/phpunit/phpunit:97 phpvfscomposer:///workspace/src/vendor/phpunit/phpunit/phpunit:97
Caused by T90875, and in particular CentralAuthHooks::onRegistration no longer finding $wgWikimediaJenkinsCI in the global scope.
But there's also the underlying issue of this code running queries in a dataprovider, which is very problematic (see e.g. T312849, T136348).