Refer: https://forum.snapcraft.io/t/x11-forwarding-using-ssh/2381/2
Solution by: jdstrand
strace was used to find solution:
Refer: https://www.tecmint.com/strace-commands-for-troubleshooting-and-debugging-linux/
Symptom:
$ handbrake-jz.ghb
X11 connection rejected because of wrong authentication.
Here's the fix for Handbrake:
ln -s ~/.Xauthority ~/snap/handbrake-jz/current/.Xauthority
Here's the generic solution:
ln -s ~/.Xauthority ~/snap/