After starting to make use of the GitLab/Codeberg sync approach for various repositories, I found that my muscle memory in Magit was getting the better of me and, on occasion, I'd push a new branch to backups when I wanted origin. I sensed there had to be a way round that.

Here's what I settled on:

(advice-add
 'magit-list-remotes
 :filter-return (lambda (remotes) (delete "backups" remotes)))

Now I never see backups in Magit and now I can keep using my muscle memory (rather than actually reading what is in front of me, it seems).