Thunderbird 91.0.3 is rendered with Hex Characters when sandboxed

[isaak654]

Describe the bug
Thunderbird 91.0.3 is rendered with Hex Characters when it runs sandboxed. Outside of the sandbox, it works fine.

To Reproduce
See https://www.wilderssecurity.com/threads/thunderbird-with-hex-characters.440046

Additional context
I'm still on 78.13.0, so I'm unable to reproduce it. However, a number of people is reporting this issue on that thread only for version 91.0.3. Multiple Sandboxie versions are involved like Sandboxie 5.47.1, 5.50.2, 5.51.3, 5.51.4.

[DavidXanatos]

There is an easy workaround, add
SpecialImage=firefox,thunderbird.exe
to your sandboxie ini

the proper fix will be included in the next build