I have the same problem on eSIM card :( In my opinion iPhone cloud loose signal during changes a mobile transmiter.I see this problem only when iPhone is in the move ( eg in car when using CarPlay). What I call at home everything is ok

Third beta resolved problem

Third beta resolved problem with IMAP :D

I see in feedback assistant that there are more than 10 similar reports. It’s very little. Quite strange

the same situation as in first beta :(

still doesn't work in beta 2 :(