This seems to be an issue. The message says TLS is OK, but the status code should be 234, not 502.
In this post, a person who seems to be one of the people behind FileZilla says it’s caused by:
There’s a bloody damn broken firewall actively sabotaging the connection.
I’m willing to believe that.
Can you please try connecting from a different network, or over a VPN and see if that helps? If it does, it does mean there is a firewall on your end breaking secure FTP.