For me the biggest issue was stagnation of the story.
Neegan was an awesome 'big bad' but it became too dragged out. Sniper rifle, tower, dead.
The trash people - seriously 'talk like that we do' in what 3 years from civilisation ending?
King with tame tiger - ludicrous
Once the zombies ceased to be a threat it lost focus.
Once they started to behave stupidly, never ending ammo, A-team style gunfights it lost credibility.
One of my fave series, but the last 3 or 4 series have all been meh.