ForwardX11 breaks mosh on macOS

I've been unable to use mosh for a while on my Mac and finally had time to troubleshoot this issue today.
This has been an issue on my old Intel MacBook Pro under Big Sur as well as my new M1 MacBook Pro under Mojave.
Mosh when run would spit out a few new lines, then just hang.
After some online research I realised there were 2 perl tasks running and killing the oldest one would then allow the connection to finish.
Some more testing showed this issue didn't happen to other user accounts on the same Mac.
Some trial and error has shown that commenting out the "ForwardX11 yes" line in my .ssh/config file has resolved the issue completely.
I do use X11 forwarding though, so was wondering if anyone knows another work around?

mosh --version
mosh 1.3.2 [build mosh 1.3.2]

ssh -V
OpenSSH_8.6p1, LibreSSL 2.8.3

perl -v

This is perl 5, version 30, subversion 3 (v5.30.3) built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)

macOS 12.1

Start by reproducing mosh on macOS with "ForwardX11 yes" in .ssh/config, comparing the affected and unaffected user accounts. Trace the SSH/X11 startup path and verify that the connection completes while X11 forwarding remains enabled.