Finally? It's been SUSE's default for at least a decade now. It's the default for Fedora since 33, so ~5 years ago. Btrfs has been working for a long time.

Yeah and it's awesome. I have it making backup snapshots automatically and I copied the steamos-readonly script from valve to automatically lock everything except my home/root/var/opt etc (I realize you can remount ext4 as ro too, but still btrfs handles this well).

I recently swapped the contents of two drives of different sizes (one was a server and the other was a PC) and btrfs made the filesystem resize and expansion parts easy.

I was introduced to it by a synology nas a decade ago, and it's my preferred fs. I wish proxmox supported it, my compute server had to go with ext4 since it's got one disk for the system, and one for the VMs, no redundancy. They say it's in 'tech preview' but most mainstream distros have had it for years now...