If you exit the vehicle (no matter which one), the screen will lock in one position and will not allow you to move from your place
The commands will also not work
The only thing that can help is:

1. Log in to the server (sometimes the game thinks that someone is still sitting in the driver's seat)
2. The /kill command in the server console, since self-input is useless

https://cursefire.com/minecraft/mc-mods/minecraft-transport-simulator/issues/1666

This is a duplicate of #1750. I see you're on the Discord, so I'll grab details from you there.