You would need to ask Google. In any event it's not anything Apple is doing; it's something Google is objecting to, and I surmise it's along the lines of what IdrisSeabright wrote.
Google is frankly desperate to make life inconvenient for anyone attempting to circumvent their information-harvesting mission. They don't want you using Safari at all, not unless you "sign in" or submit to ever-increasing demands to accomplish that mission. It's their lifeblood.
Yes a VPN could interfere with that mission. Also, Safari incorporates a number of privacy protection features that Google really, really doesn't like: Safari Privacy - Apple