Just as a reminder for myself. Once in a while I have to update Jetpack Social with a new connection (e.g. Bluesky today) and it throws the above error. This is because XMLRPC access is disabled. I use Cloudways (referral link if you feel like signing up) and its something to be toggled there.
Enable it momentarily, do the additional connection, then disable. Inconvenience is the price we pay for security. š