Flo Lieb’s review published on Letterboxd:
I understand the need for levity in this overall grim and bleak story but overall Bad Ape was a bit much in regards of comic relief. Especially when you already have MVP Nova to make things lighter here and there.
About that whole "mute"-ation of the Simian Flu - I'm kinda torn. Sure, there might be some ironic poetry in terms of the diametral evolution of the apes and regression of the humans but we never really saw a fully "regressed/animalistic" human to fully grasp the outcome (Nova didn't seem like an animal throughout).
Therefore I'm also torn in respect of the premise and plot. The mutated virus should be the bigger concern for the Colonel, especially since Caesar gives multiple signs of peace and mercy. Why go after the apes who currently aren't even a threat? Of course to collide the characters of Caesar and the Colonel. I didn't really buy Harrelson as the ruthless soldier, a mixture of his character in Rampart and Brando's Col. Kurtz. It may be typecasting but someone like Stephen Lang immediately comes to mind.
Questions arise also concerning the speech of the apes. As Caesar gets more eloquent each movie all of the other apes make no effort at all. Not even Blue Eyes who shares his father's gene pool. It certainly isn't a matter of ability but one of choice. Maurice can speak if he wants to, Bad Ape speaks nearly as good as Caesar, so surely Luca, Rocket and the others are capable of expressing themselves vocally but simply chose not to. Maybe since spech is a tool of humans. Which makes it odd that Caesar mostly communicates with his tribe vocally and not via sign language (amusingly the other apes even talk to him in sign language even if Caesar isn't looking at them but still takes part in the conversation).
If this marks the end of the Apes-reboot (or at least this Caesar trilogy) it's an okayish farewell - albeit ultimately an unnecessary one since it basically just ends in a place like Rise did.