Similar to T337943 the CheckUser prune job (checkuserPruneCheckUserDataJob) should also remove client hint data. The prune job is triggered on average 1/10 times a RecentChanges entry is saved and deletes expired entries in a similar way to maintenance/purgeOldData but doesn't prune the recentchanges table.
The job definition is at src/Jobs/PruneCheckUserDataJob.php.