Why do deleted emails reappear in my Apple Mail inbox?

I am using Apple Mail (Version 16.0 (3826.600.51.1.1) 1995-2025) via my MacBook Air M4 Sequoia 15.5.

Often, when I delete an email or a number of emails in my Inbox they re-appear in my Inbox a minute later ... even sometimes if I'm fast and I delete /empty the Bin.

This doesn't happen on my iPhone, so if I read and delete my email via my iPhone my Mac email will correctly update to reflect that of the iPhone.

Is there an issue, or is there a sync issue, or something else .. very strange ..

It only happens on this one email account (btinternet) whereas the other 2 emails accounts use another email provider and are fine.

Any help /advice most welcome

[Re-Titled by Moderator]

Original Title: Apple eMail: Deleted emails re-appear in Inbox