Google is just weird about that stuff. I've previously had the issue where me and someone else on the same workspace with the same domain had lots of back and

Google is just weird about that stuff. I've previously had the issue where me and someone else on the same workspace with the same domain had lots of back and forth and suddenly Google decided me sending them a reply was spam. Both were authenticated while sending and it was in an email chain. It's like, everything signals "this is fine" but their filters say "no, this must be spam". Eventually we just both used our non-google private email accounts because using the work emails was just not reliable enough. I have no idea why people use any Google communication products, missing legitimate email is much too high a risk for me.