The delete can be flaky sometimes. Sometime you have to delete a row multiple times before it goes away. I think it’s a sync issue between glide and the local copy if you are making too many changes at once.
I don’t see anything wrong with how you did it. It seemed like you did it slow enough. I’ve never had to mass deleted a bunch of rows. At most a few here and there and I have seen rows come back on occasion, but not all of them. It does seem odd that they all came back…and in multiple tables.
At this point, I would suggest submitting a support request to glide.
@Anu_from_Restogy report as defect as Jeff suggested.
Until we get a good mass deletion functionality in glide you can use a robot to help you complete the task