You can discuss potential bugs and buggy behavior here. If you are certain about a bug and have reproducible steps, go to the issue tracker and search if it’s a known issue. If not, create a new issue and be proud, your contribution is appreciated! If that doesn’t satisfy you enough, submit a pull request and make us all proud.
If a bug is submitted on github and is critical, it should belong in this Critical list. This is for show-stoppers that we like to take care of as high priority issues whether they belong in the current milestone or not.
If you run into any BTRFS or OS issues, this may not be the best place to start a topic. Instead choose Troubleshooting category.