Godot's issue tracker is very popular! There have been ~4700 issues created this year, more than half of which have been closed, with ~2000 currently open.
Also of note, there's an open proposal[0] 'Automatically close old issues in a way everyone should be happy with' attempting to deal with the significant backlog.
Actually it's 8000+ open issues on Github. It seems the number is capped at 5k in the header of the Github webpage. On the other hand, it's got 34k closed issues, so it's not as if the devs weren't working on this
Again the number of open issues is not a good indicator of software quality anyway.