Fedora 33 introduced a new default filesystem in desktop variants, Btrfs. After years of Fedora using ext4 on top of Logical Volume Manager (LVM) volumes, this is a big shift. Changing the default file system requires compelling reasons. While Btrfs is an exciting next-generation file system, ext4 on LVM is well established and stable.

Source: LXer – Choose between Btrfs and LVM-ext4