Mail app auto-archives IMAP emails on Sonoma 14.5

I have a problem with the Mail App (16.0) on my 2020 M1 Mac Mini running Sonoma 14.5

Suddenly when searching I started seeing the messages double, one in inbox and the other in folder with name like 2025-12. I have found out that for several IMAP accounts Mac Mail has started to automatically copy into Archive folder (sorted by month) my e-mails. All of them from inbox and from sent messages.

I have several IMAP accounts and for some this happens, for some it doesn't. They are not gmail accounts, they are normal hosted IMAP mail accounts.

Started happening in December, with no change to the system or settings initiated by me.

Account setting seem similar with the accounts where it happens and where it does not happen. I have no rules setup and those e-mails are hosted on the same server (where it happens and where it does not happen).

One of the e-mails that does it is not setup anywhere else, so I know it is not outlook or any other program causing this.

I am quite unhappy, because it makes a huge mess.

Is this a problem for anybody else? And is there some solution?