Please explain the motivation behind the feature request.
There are over 1000 branches, things start breaking with this tech debt. Similarly can dismiss old issues with no activity.
Describe the solution you'd like
A simple solution is to auto-delete branches that are accepted and merged. Git history allows reverts, there is almost no reason to keep these branches around.
Describe alternatives you've considered
Protect only a few main branches. Allow old issues to be marked stale for x amount of time before deleting.
Additional context
I'm sure there are other ideas to keep things tidy!