The way that favorite works it is a little odd, and it is possible that you have all the jobs in your Jenkins as favorites without doing anything, it is my case, I make PRs to ever repository on our organization so every time I make a PR BO adds this build related (multibranch pipelines) as favorite, here is were Jenkins and I start fighting to remove favorites from my user profile and it adding more, he wins always and I have all projects as favorites. My suggestion is to remove this feature that adds PR as favorites or at least enables some way to disable the feature for every user or one user

https://jenkins.io/doc/book/blueocean/dashboard/#favorites-list

>Blue Ocean automatically adds branches or PRs to this list when a they contain a run that has changes authored by the current user.