The problem as I see it is Gunn made lightning in a bottle with GotG 1. None of the characters were that smart, but they all had heart, and just over all it was just a good funny comic book movie. The charm of that specific team is they not too bright but they will get shit done.
So marvel decided to "Gunn" every single movie after that. Now all the characters are dumb. Now they all have to make even more quips after every single line. If you go back to the movies before GotG yeah they joked around, but it wasn't literally every other line. The recent movies need to do it as a response to anything a character says and it doesn't matter if it's appropriate or not. Because Gunn had dumb people laughing at each other, so now everyone must be dumb and laughing at each other.
Guardians 2 was alright. It goes too far into the dumb joke reactions though. But again that's who those specific characters are, so whatever.
Then Gunn makes The Real Suicide Squad (I can only guess it's because The Real Ghostbusters wasn't available). Lots of dumb villains on that team. There's a lot of heart in them though...
And finally there's Peacemaker. The show where not a single character has any intelligence. Every chamber is racked with morons saying stupid things and making fun of each other. It's funny, sure. But even Wallace is played like someone that can't process more than one thing at a time.
I like the guys stuff, but this is how his movies have progressed, and the other people making movies in the same genre are tripping.over themselves to be him. Now he's the show runner for DC. Will Gunn reload and make movies that fit the tone for each DC character? Or will every single character from Superman to Alfrid Pennyworth be dumb as rocks and all make fun of each other every other sentence?
That, my dear readers, we will only know in time.