Speaking strictly for myself (i.e., this is an opinion, not a fact!), I'm critical of most people who arbitrarily report a "bug" following a firmware update. In fairness to most of those, yes, there *are* often problems discovered following a firmware update. Most of the time they don't seem to be some kind of vicious, fatal error and places like a forum is a great place to find out what others may or may not be experiencing.
The one big "bug" that drives me crazy is not really a bug (it sure as hell isn't a feature!) is when a new firmware update mysteriously alters or resets things like the RTH-Altitude (and others that can be time-consuming to check as you wade through a litany of menus and checklists).
Another "bug" that isn't really a bug but might seem to be? I wonder how many users truly know all the subtleties of the RTH? Set everything up, run through your checklist and take off. Fly gently out away from where you're standing until you're out over the water (I fly a lot over a lake). Let the quad hover, then turn to your friends and say, "..now watch how this return-to-home function works." Press the RTH button and then watch in horror as your drone starts to descend EXACTLY WHERE IT IS! Hopefully, you know to "lean on" the RTH button again, stopping the auto-land that's now taking place.
If you scratch your head, trying to figure out why your quad appeared to have a mind of its own, it means you probably didn't read the manual and see the part where the RTH function is fully explained - if it isn't very far away from its home point, when the RTH is engaged, the quad will attempt to land. The hardware/software in your Phantom has assumed it's safe to come down right where it is.
Is this a bug? Someone who didn't read (or didn't read very much) of the manual might think so.
RTFM and practice, practice, practice!
Art - N4PJ
Leesburg, FL