The Problem
"The problem seems to correlate with a weak GPU and the game is timing out from the server, so if the GPU is the problem, lowering the graphics settings to the minimum should fix the problem.

The problem seems to be related to RAM usage, once you hit around 2GB of RAM used, the game will crash. Servers with many addons have much more RAM usage, and lowering graphics settings to the minimum lowers RAM usage and mitigates crashes."-(section 4.64.3) https://wiki.archlinux.org/title/Steam/Game-specific_troubleshooting

More Ram
By default Gmod Uses 2gb of ram, if you have more ram, on the hl2.sh file under the main game directory "GarrysMod", you can change it by opening it with a text editor, just remember to leave some ram for the system or it will probably Freeze.

Testing
I will be testing more into this since is correlative to what version you use of both Proton and Native Runtime, or also if you don't use any compatibility tool (you didn't went to the menu to select a compatibility tool before).