Double mailbox in Apple Mail

Hello

I just installed the 11.1 Update for Big Sur and my Apple Mail side bar changed

When I first set up my computer and Apple Mail I added a Pop Account "called" Velarde and I checked my mail this way.

I also created several Mailboxes to organize all my mails and everything was working on OK under the "On My Mac" Mailbox. This is how I want it.

But I just installed the Big Sur upgrade and now I also see a "Velarde" account in the Sidebar.

Which is basically the same account I had minus the customized Mailboxes, The Inbox count is the same...

If I uncheck the "enable this account" checkbox the Mailbox (or is it an account?) disappears from the Side bar , but then I can't receive mails in my computer...

I want that to go away as I had it before the upgrade.. It's a little bit annoying to see the inbox # double...

I just want to see "Favorites" + "On My Mac"

Can somebody please advise on why this happened and how to solve it? Thanks for your help