Fatal error: Allowed memory size of X bytes exhausted (tried to allocate Y bytes) when Scheduled Purge of Finished TMGMT Translation Jobs

I'm running into the same issue, but when deleting a bunch of translation jobs in an own update hook. The problem is that Drupal\tmgmt\Entity\Job::postDelete() loads all job items at once in order to delete them, but if this was a long-running job with a lot of job items memory issues can arise even after deleting only one job.

I propose loading and deleting the job items in chunks.

I had the same issue and finally i have used the same setting 'job_items_cron_limit' to use it also for the finished items, in case that the user has not enabled this setting, the limit will be 50 by default.
Hope this will be heplful.