I can't even get Gmail to deliver my 100% genuine, properly authenticated, sent-from-my-own-domain-which-has-never-sent-spam firebase sign-in emails - and it's

I can't even get Gmail to deliver my 100% genuine, properly authenticated, sent-from-my-own-domain-which-has-never-sent-spam firebase sign-in emails - and it's the same parent company! The get sent to spam or (worse) silently have the links stripped out a decent percentage of the time