I've seen this a lot and I don't really understand why people take issue with it.
Tyrion played a neat little trick at Blackwater with wildfire, but aside from that what has he ever done to make anyone think he is a military genius, or a brilliant tactician?
...
Experience as a battle tactician or not, Tyrion is intelligent. Most of his plans this season don't line up with what I've come to expect from him as a character.
I mean, let's start with the idea that laying siege to King's Landing is somehow 'better for the people' than attacking with the dragons. Is this not an utterly ridiculous idea? It's not Cersei or the soldiers that would be starving to death in that situation - it would be the lowborn people of the city. Tyrion would absolutely know this. It makes much more sense to attack quickly and decisively, but the show needs a way to justify Cersei's continued existence, and Tyrion becomes the fool.
Then there's the fact that Tyrion was literally the Master of Coin for a time. I find it hard to believe he wouldn't be aware of the dire straits the Lannisters were in with money, or at the very least that the mines of Casterly Rock had started to dry up. I know Tywin likely wouldn't have told him, but Tyrion is a perceptive fellow, and there would be other signs. Even if he somehow hadn't picked up on any of that - he was
definitely aware that the Euron had aligned with Cersei. Pyke is very close to Casterly Rock. The idea that Tyrion would fail to anticipate an attack from there is ridiculous tbh.
Seriously. But Cersei needs to gain an advantage in the war, and so Tyrion becomes the fool.
And then as I said before - the movements of the Lannister forces don't make much sense unless they have perfect knowledge of Daenerys' plans. How did Euron know he'd find Ellaria and the Sand Snakes aboard those ships? Why would the Lannisters extend themselves to the South to attack Highgarden (in what should realistically have been an incredibly long siege - we're talking months at minimum), when as far as they know Daenerys could be attacking King's Landing at any moment? Moreover, how is Varys, the 'Master of Spies' not able to gain any intel in the other direction? Because everything this season is contrived, that's why. I have expect them to reveal him as a double-agent in order to justify all of this, even though it would make zero sense whatsoever.