This happened to me with AWS somewhat recently[0], and I never found out exactly what happened. I just chalk it up to some dev made a mistake and didn't tell anyone. It's pretty alarming when things like this happen though. 0. https://news.ycombinator.com/item?id=21326014
they e-mailed me saying they deleted some domains not because some entries were broken or had problematic entries, but just because it was "underused", i.e. too few DNS resolve calls. So the tiny data packets in their nameserver caused them unnecessary consumption of electricity or whatever. Very compelling! This is how they do business these days.
They bombarded people with all sorts of useless info, but not about this policy of theirs. Makes you feel very much like the proverbial "valued customer".
Everything is going downhill in this century, that's a fact.