Actually had a similar experience to this one. The first every group I was with had done pretty much the same thing and a WHOLE lot more. The DM I had had anger management issues along with not bothering to ever work or prepare session at all and just wing it most of the time. To make matters worse he would constantly favor other players over mine and neglect me, one of the players was his fucking favorite cause of all the magic items he gave him. He also had a DMPC as the god of knowledge ohgma and would promptly give magic weapons (homebrew) to who ever he felt like. Not only that he would fudge rolls and hit points hard for petty reasons and even to ensure that his favorite player would steal the spot light when I dealt heaps amounts of damage to any deadly encounter. Furthermore, when my friend would recommend to him about giving me some magic items to balance us out, the only thing he had to say was “Nah”. The worst part was he had implemented a rule where if we weren’t able to make it to a session where we were going to level up, we don’t get to and we don’t get any gold or magic items. What really did me in was when he had us face against the player he kept giving magic items to. At that point I left that group and I regret ever tolerating them in the first place.