In my opinion, if you upload a mobile game on Itch that has ads, it is a game that is so bad or violates some quality guidelines (like shovelware), that google would not accept it.
And all such games I have seen on Itch were crappy shovelware slop. Usually made with those cookie cutter template websites that promise non coders you can make a game with no experience. The adservices are already included. And a lot of those I only noticed because the developers whined about not having their shovelware slop being indexed right away.
Also in my opinion it is actually forbidden to upload such games to Itch without making it clear, that it is adware. Not telling people shifts a game from having ads to the category of malicious adware imho. On google you can see such things before downloading at a formal systematic level. Itch has no such facilities, because it is not an app store for mobile apps. You need to spell it out.
https://itch.io/docs/creators/quality-guidelines#avoid-obtrusive-advertisements-...
Any projects that contain malware, spyware or adware are prohibited and will be banned from our platform.
Forpeoplesmall indie teams who have released a free game, how do you decide whether to add ads or not?
A small indie team is a small game studio. You are not talking about a bunch of friends releasing a fun games for the fun of it, or are you?
A game studio will make the decision how to market and monetize a game way before release and not after release. It is a business. They need to pay their own wages. While you can do things without having a business plan, it is also a quick way to failure.
Anway, Itch is not a good platform to monetize games with ads, microtansactions, in app purchase and so on. It is not even the right platform for typical mobile games. The users here will be cautios about such things.