@marcel, can you try this on a test site (if you have one) –
1. Create one or two schedules as normal with whatever settings.
2. Then create a 3rd schedule, with a end date one or more days in the past and set it to auto-delete on expiry.
3. Wait out the maintenance routine (or run wp-cron manually).
Are all 3 schedules deleted?
All schedules created before the auto delete one ‘should’ be deleted in this scenario.
Adverts or settings for them are not relevant in this test.
It’s purely about schedules and the auto-delete setting. Also the one set to auto delete should be created (among the) last.