There are so many alternatives to email -- Outlook, Yahoo Mail, Proton, iCloud, etc. How can you argue with a straight face that Google has a monopoly on email?
* they do provide customer support, it could obviously be a lot better
Providing something for free is not a defense against anti-trust law.
The most famous example showing this, was regarding internet explorer, which was provided for free, yet anti-trust law effected it anyway.
Just because unicycles exist as a means of locomotion doesn't mean that personal transportation isn't dominated by automobiles.
Of all the services Google has, email is the least monopolistic, but simply because there is competition in email an open standard that many companies (including google) have tried to make less open does not change the Fact Google has market dominance in many other services