Yes. Our company backs up pretty much everything.

The snarky answer is that if you have n developers, you have n backups of your git repositories.

Daily backups of our (self-hosted) GitLab, rsync-ed to a remote machine, and from there, BTRFS snapshots onto a removable HDD, which is rotated off-site every week.

The answer should be YES for every company which has infra engineers.

What about Issues and PRs too?

yes, and you absolutely should