To the author, I wish you best of luck with this but be aware (if you aren't) this will attract all kind of bad and malicious users who want nothing more than a "clean" IP to funnel their badness through.
serveo.net [2] tried it 8 years ago, but when I wanted to use it I at some point I found it was no longer working, as I remember the author said there was too much abuse for him to maintain it as a free service
I ended up self-hosting sish https://docs.ssi.sh instead.
Even the the ones where you have to register like cloudflare tunnels and ngrok are full of malware, which is not a risk to you as a user but means they are often blocked.
Also a little rant, tailscale has their own one also called funnel. It has the benefit of being end-to-end encrypted (in theory) but the downside that you are announcing your service to the world through the certificate transparency logs. So your little dev project will have bots hammering on it (and trying to take your .git folder) within seconds from you activating the funnel. So make sure your little project is ready for the internet with auth and has nothing sensitive at guessable paths.
[2] >>14842951
It's still live though.
I had done some account filtering for origins coming out of Tor, VPN networks, data centers, etc. but I recently dropped those and added an portal page for free accounts, similar to what ngrok does.
It was very effective at preventing abuse. I also added mechanism for reporting abuse on the safety page that's presented.
[edit] for clarity