GTAsus is a simple batch script that uses pssuspend64 to suspend your GTA V process, which disconnects you from all the users in the lobby. This makes all players 'leave' on your end, and you will have your own private public lobby!
Due to the Sysinternals license agreement, I cannot provide pssuspend64. You must download it from https://docs.microsoft.com/en-us/sysinternals/downloads/pssuspend.
Simply get pssuspend64.exe and put it in the same folder as the batch script, and then run GTAsus.bat.
This is for Windows only, but it could possibly be done on other operating systems with a Python script.