I’ve completely restarted the tunnel a few times to see if it would stay the same: it did.
But will it always stay the same or will it change every once in a while?
With the current version of playit it will always be the same as long as you get connected to the same tunnel server. When new tunnel servers go up or old tunnel servers get shutdown, your IP may change. The randomly generated auto.playit.gg domains will remain static and always point to your tunnel (it automatically updates).
With the new version of playit that’s in private beta this will be different as each IP will be on every single tunnel server.