Gradio's reverse proxy service sucks. The WebUI program integrates ngrok to fix this issue which works well but Paperspace locks your account for using any tunneling proxy service such as (who knows how many they explicitly ban).
There is literally no easy solution for this and you must to host your own server that Paperspace doesn't know about. What I do is run a rathole server on a $4 DigitalOcean VPS.