There hasn't really been a significant change to the image. Our images do get refreshed for package and os updates weekly, that's why you see the update notification. The changelog on github or docker hub tells you the changes to the image other than package updates.
In your case, make sure that the ip on duckdns matches your home ip. And also make sure that nothing changed with regards to the port mapping on unraid and port forwarding on your router.
You can remove the only subdomains or set it to true but keep in mind that when you do so, it will try to validate the cert again and if there is a port related issue, it will fail. So you should perhaps wait until you figure out the connection issue before changing it.
Another issue can be that your client ip may be blocked by fail2ban if you had isuues with authentication (not sure if you use htpasswd).
Try connecting from a different ip, on a mobile phone through the cell connection, etc.