No You do not have to have a separate non BTRFS boot.
BUT If you hibernate or use the boot to other OS option on shutdown then you do need one. The reason is the in those circumstances then Grub needs to write to a file in the boot partition and it does not know how to write to BTRFS. Oopsie
This is a known problem for some time. But it either was not fixed or the workaround does not work I suggest that if you really don’t need the bells and whistles and want to avoid problems with BTRFS in fairly common circumstance then use ext4. Nothing wrong with it it ain’t broke and you won’t see the problems that BTRFS can cause. Of course there is nothing wrong in trying a new FS out and there are some interesting features but for a simple desktop why do you need them??