Sorry, but this sounds a bit terrifying. All your traffic is going through Bubble's servers where it is TLS-intercepted and accessible as plaintext. Compared to a browser extension like uBlock, you don't see what is happening on Bubble's servers. You essentially need to trust a startup with all your internet traffic.

The claim that it's "open source" a bit disingenious after looking through your GitHub repositories. It's not like you could test Bubble locally and then decide to use your hosted service.

I think the overall use case is solid, but would be much better served with a browser extension. Also, very likely mitmproxy won't really scale that well to lots of users.