PSA: #Linux 5.16 introduces an issue with #btrfs where btrfs-cleaner might "spin forever", cause 100% cpu load and issue a ton of writes [1]. My 256GB NVME drive got rewritten 10x over in less than a day before I figured out what's going on. There's a series of patches being worked out [2] but in the meanwhile what worked for me was turning off 'autodefrag' in /etc/fstab.

[1] https://www.reddit.com/r/btrfs/comments/s4nrzb/massive_performance_degradation_after_upgrading/
[2] https://lore.kernel.org/linux-btrfs/CAEwRaO4y3PPPUdwYjNDoB9m9CLzfd3DFFk2iK1X6OyyEWG5-mg@mail.gmail.com/T/#u