All I can add is that I'm very glad that I've no Google accounts nor use its services even though I've an Android phone.
I hope the younger folks learn better the lesson to own your nameplate - even if you just end up forwarding message to gmail or what-not for consumption, keeping control of the nameplate gives you the flexibility to shift later on.
Recently some Discord channel started using some other weird "verifier" bot plugin thing and they refuse, claiming my long-time personal domain is "high risk" for no discernible reason.
I'm scared of a future where you have to be in the positively good graces of 4-6 email/SSO monopolies to avoid becoming a digital nonperson.
Discord is speed running how to be a garbage company.
The unfortunate reality is that if third party disposable email services didn't exist then it wouldn't have such a distrust for random domains. Anyone can just throw up an email service on a new domain and then anyone can start using it for fraud and abuse. If you've never run a freemium service then you might not know just how wide scale this sort of fraud is
I went into internets in 1995. Must I tell you about fraud and abuse in early 2000s?
Blocking domains is a cheap shot. It ticks a box somewhere maybe, but it does not and can not prevent or mitigate.