Seems to be standard functionality according to this:

https://fedi.tips/how-do-i-delete-a-post-on-mastodon/#:~:text=There%20are%20actually%20two%20delete,make%20changes%20and%20repost%20it.

According to the same article it can fail if the server is malfunctioning. But I would assume only rogue servers would do this intentionally...like suddenly kick all users or a particular user out and lock them out of their delete option.