История изменений

btrfs-filesystem(8):

The resize command does not manipulate the size of underlying
partition. If you wish to enlarge/reduce a filesystem, you must
make sure you can expand the partition before enlarging the
filesystem and shrink the partition after reducing the size of
the filesystem.

Ты пытаешься изменить размер файловой системы, а нужно вначале изменить размер самого раздела через gparted/fdisk и не забыть сделать partprobe.

btrfs-filesystem(8):

The resize command does not manipulate the size of underlying
partition. If you wish to enlarge/reduce a filesystem, you must
make sure you can expand the partition before enlarging the
filesystem and shrink the partition after reducing the size of
the filesystem.