[deprecated] Wikimedia\Rdbms\Database::selectSQLText: aggregation used with a locking SELECT (NewsletterDb::addNewsletterIssue)
Given it is a deprecation warning, it most likely means things are working as intended today. But this may stop working in the future.
Querying Logstash over the last 30 days, shows it's been triggered every week, so likely this is not a recent regression. The detection for this issue was introduced in 2018 as part of https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/425731/.