Mail moving some messages from inbox to trash on mac, iPhone, iCloud

Running Mac Sequoia 15.6.1, iPhone SE IOS 18.6.2, logging into iCloud from Mac using Safari 18.6.

Certain senders' email goes to trash (iCloud, iPhone) or deleted folder (Mac). If I move them to inbox, they move right back. This happens on all 3: iCloud, iPhone, mac. It seems to be selective: a major delivery company, a major online billing company (no not that one), some genuine junk, some not junk. Some very important. Senders affected are not predictable. I certainly didn't see this one coming.

I discovered the problem on the Mac, but after attempting to move the messages and having them pop back to deleted/trash, I checked iCloud and iPhone and it was the same thing.

I deleted all rules. I rebuilt all mailboxes on Mac. I looked at mailbox behaviors. I turned off all junk filtering. I got out my ORACLE 2.3 and Kaypro 4 manuals and went looking for unicorn horns.

I have spent hours on this. I can't keep losing invoices and delivery notifications. It has caused a lot of embarrassment and some late bill payments.

I saw lots of search results, but couldn't find any question on search that is less than 2 years old, the advice was things I've already done, and sorry don't have more hours to spend going through 1300 search results.

Any ideas? I have always (2005) used Apple's mail but so help me I'm ready to go back to eudora or "You've Got Mail!" (I won't mention what Music did to me just now)