Honestly I saw btrfs in the arch install guide and read about it because I thought the name sounded funny. I used it until I distro hopped to NixOS couldn't figure out how to install it with btrfs, so I'm back on ext4.
Maybe I'll give it another try next hop, which is likely soon since Qt theming seems impossible on Nix. :/
Yeah, I did find the page, but it assumes you're doing a command line install whilst I was using the graphical installer. Now that I know more about Nix I think I should've gone for a CLI install, but I don't know if I will stick with it due to the themeing issues.