I'm not sure which product(s) you're referring to.
Apple has like 6 apps in the Play Store and one of them is for helping Android users migrate to iOS. On the other hand, Google has dozens of apps in the App Store.
And Flutter Web not working on iOS doesn't even help Google. If anything it just hurts Flutter's adoption on the web which is already low. So I don't think there is some grand conspiracy within Google to take out Safari by withholding Flutter support.
They sort of gave up halfway through lazily invoking the NPC bog-standard Google-on-iOS complaint: you need to pay for YouTube Premium to watch videos picture in picture over other apps.
(source: iOS dev turned Googler turned ex-Googler, so I soak in everyone's grudge matches :) )