Hmm. Perhaps Google is considering dumping some of their iOS apps then. Gmail would certainly be a prime candidate.
People are assuming this is about the privacy label, when it may be more about the 'opt out of tracking' button.
Seriously doubt it. Gmail has 53% of the US email market, 130.9 million users. And iPhones are over 50% of the US smartphone market; about that same 53%
With a good chunk of people using the Gmail app. It has something like 8 million downloads per month.
I would say that is not very likely since access to the service is how they make money.