I have taken a break of the hobby for couple years and have trouble reconnecting with my former ATFs by gmail. Did google block gmail of known providers due to FOSTA/SESTA?

Many providers and clients switched over to Proton mail thinking it was safer so perhaps they no longer use that gmail account.  

mine was blocked, reason I went to email only for communications and use proton.ch

Turban, did they say why you are banned?  Regardless, google must be able to read into the contents of the gmail, a violation of mail privacy.

nothing "illegal" communicated thru that phone number. Simple was an auto message on you to find me.

VT,
Please make sure it's not Google spam that blocked you.
THERE is a spam/scammer...posing as (goggle support team)  
Telling you they will block your email etc. If you don't contact them or cluck on a link.  
It's a SCAM