Do our external backup drives have to be APFS to be compatible?

MacBook Air Monterey, had this issue of ejecting drives while trying to get a Time Machine back up done. Tried many suggestions here, nothing worked. Used disk utility to change my Seagate 1TB external to APFS and now I don't get the disk eject error. Note it backs up much faster now. I'm no where near knowledgeable on these issues just sharing what worked.