Blocked using [] - Error: open resolver

suddenly from today all my domains when sending started getting this error :

Server error: ‘554 5.7.1 Service unavailable; Sender address [MYEMAIL@HOST.COM] blocked using; Error: open resolver; DNSBL Error Code - Open/public resolver - The Spamhaus Project

The IP is not related to my site or mailbox - this is Cloudflare IP, and the only thing related is that DNSes are on CLoudflare (but not proxied)

spamhaus shows no blacklist by my domain or ip.

Anyone can explain whats happening and help me please?

OK, disabled spamhaus checks in /etc/postfix/ , this helped, however why and how this happened ? Was this a part of autoupdate ?

Are you letting the box handle DNS? Or are you using the dns server of your provider?
What does the status page tell you regarding spamhaus blocklist?

DNSes for both MIAB and domains are on Cloudflare, however this setup was working for 6years until yesterday

Same problem from today
VPS - nginx steam ports - VPN-host

If you use Cloudflare you need to take the below in account. This has come up a few times