I'm in a similar boat; been running email servers since before GMail existed. My personal one I've been running out of a home server closet since 2001. I've also done everything I can to guarantee I'm not running an open relay and not sending email unsolicited. Have been mostly lucky so far, but occasionally I will have people on mailing lists I manage (people I have met IRL and put them on the list to organize group meetings IRL) not get email. Used to be other stupid mail providers (AOL comes to mind), but these days it appears to be Google, sometimes.
I've had this domain nearly twenty years and run email on it for that same amount of time. I'm not going to "just switch", especially to a privacy invading ad-spewing "alternative" that doesn't give me as much control. Fix your damn servers, Google.