Why? Are you paranoid and odd?
I'm definitely odd that I read the stories of unlucky people's entire lives F'd over because they happily used all the standard convenient google services and then google killed them, in error, and with no human customer service to correct it, and I decide that maybe we shouldn't all just cooperate with a bad thing, and try to get myself some other service providers.
I already have my domain firstlastname.com with Google domains. I can setup email forwarding for free. All goes to my gmail address.
As far as normal people their reaction was "That's cool you have your own email like that"
So I have a .family address for my “primary” account and a gmail account for fallback purposes.
I also sometimes use first@firstlast.com because some services don't allow emails starting with keywords, Facebook for example doesn't, or didn't at the time I tried, allow mail / info / admin etc.
While they are pre-judging others for not using gmail because they see that as weird, I am a valuable capable potential producer judging them for their failings of both academic integrity (as in you just shouldn't do that simply because it's not right) AND also seperately for their failing of pure intelligence and their own self interest, because in fact some of the smartest most capable people are the ones willingly and knowingly taking on the burden of not using gmail for either practical or principled reasons, and they are filtering those people out, which I judge to be stupid. Those are probably exactly the most valuable people to their own interests.
While from the other side, I don't necessarily consider it to be stupidly filtering out potential employers, because I am not desperate for any scrap of employment.
I haven't noticed any special problem with my own PM address, but I have never tried to cold call anyone from it. So I would possibly agree that filtering out 90% is too much even if I'm not desperate, but I haven't encountered that problem because I'm not trying to contact a large number of new strangers.