Raid5 on btrfs is not and has not been production ready. It's available in the code, but with appropriate warnings. You're not supposed to be using it, rather than it being "unacceptably risky".
That's the problem with btrfs. Raid5/6 still isn't production ready and loses data with cheap consumer ssd which could to disappear/reappear in a running system. On the other side raidz/z2 works rock solid. Of course I could use btrfs with mirrors instead but that's the reason why I use cheap consumer ssds. I can't spend that much money just to use btrfs so I stay with zfs.