Some emails immediately disappearing upon opening.

This had started about 2 weeks ago with my comcast.net email acct. around the end of February 2025.  When opening an email, I click on it and poof, it's gone!  I eventually found that the only way to retrieve that email is to do a search of the subject in the "inbox" and there it is!  I now always have to be extra aware before opening an email who it is from or the subject so I could do that search for it if I lose it.  It doesn't happen with every email I open but enough to be very strange and inconvenient!  I'm wondering if anyone else is experiencing this recently?  I've been a comcast.net user for as long as I can remember.