I don’t think Tailscale counts as a reverse proxy, but it does support HTTP/3 and QUIC so that suggestion may not apply here. Still, it might be worth double-checking to see if they are disabled. Also, have you tried disabling Tailscale altogether and connecting directly?
I believe ytDownloader might be what you’re looking for. It’s a yt-dlp frontend, you can export to video/audio pretty easily. And it’s in active development. I’ve used it to export short clips to WAV a few times, nothing too fancy, but so far it works pretty well.