I remember there was something like this but it was on Counter Strike, it was called KAC and it was like VAC but banned people for cvar hacks and servers could decide if they wanted to activate the global ban system, it was a useful tool because only the software could ban.
Honestly this should be optional and should just run off lua and DLL if it’s really needed with ban.garrysmod.com with the global ban list. Server admins download off the sub-domain. When an admin flags a user it goes straight to the website and the user is banned locally (FOR HOW MANY DAYS THE ADMIN DECIDES) and people decide what they think. It will also have a list of “Servers user is flagged on” that tracks the users steamID… This helps moderators understand that this user may be an annoyance on other servers.
The user will go on the flag list and people can input there views with an X and a tick with a comment system. Moderators who are the people who decide if they go on GGB list, users can also input proof either it be youtube videos, demos, screenshots etc. this would help mods who have no freaking idea who they are.
Once the user is banned, he/she will be disconnected with a “GGB black list user” the bans are permanent and users may wish to appeal ONCE and if it’s denied then the user can not be unbanned off the website it will need to be changed in the .dlls and possibly .lua (I don’t know much about it)
If this is already included in the .pdf, sorry I didn’t read it I am in a rush.