At first I thought the fact the advertising-and-tracking company needed access to their competitor's encrypted messenger was related to the tracking that is their core business model.

But it's unfair to assume bad faith like that.

Perhaps they merely need access to the encrypted messages in order to provide a better user experience, by serving more relevant and better personalised adverts?

I'm not going to argue there's any bar too low for Google to not clear, but also, it really is possible that it's just for the stupid AI feature they say it is. Just because it's something Google could feasibly do doesn't mean they will. I'm very confident they have never used Google Public DNS for advertising or tracking.

It's one thing to treat funneling data "to the cloud" with suspicion out of principle, but personally I think it's counterproductive to go a step further and just assume everything is always being maximally abused. The fact that it could be is an issue, but that doesn't mean it is.

It does when it that person is taking a charitable view of anything Google has done since about 2011.

That may mean they're stupid but it still doesn't constitute bad faith. Do you know what "bad faith" means in this context?

Bad faith typically encompasses willful blindness and deliberate ignorance. There’s a reason why courts can equate not knowing something when you should have and chose not to, with actually knowing it.