Version: 1.20.1
Mods: Only Mod Menu and ModernFix
Here is an image of the TubNet lobby on 5.11.1:

Here is an image of the TubNet lobby on 5.11.0:

Here is a link to the log file for 5.11.1: https://mclo.gs/A1Omcmu

This does not happen with dynamic resources off

Here is a link to the log file for 5.11.0: https://mclo.gs/zvFgcv5

Btw I'm a community tester for tubnet.gg. Would you like me to ask them to fix their model files, like you mentioned in the commit? If so, give me a full rundown of the issue so I can forward the request.
No guarantees that it will be fixed though, since they probably care more about supporting vanilla than supporting mods.

Wow that was unfortunate timing, Tubnet is shutting down on the 12th so you no longer have to worry about it :P

The underlying issue is fixed in 5.12.0 regardless.