If you make your tailscale available to the internet through tailscale, you are still weak to external attackers, putting a VPN in the middle doesn't fundamentally change that dynamic, maybe it shifts it around and it confuses you enough to feel less shifty about it.
But it doesn't decrease your risk, if your HTTP server is weak to a tailscalething.tld/../../etc/ attack, it doesn't really matter that requests to other ports are blocked, (which probably don't even have processes listening anyways)
Not if it's a private server, like the poster above was describing. For example, if I want to maintain a NAS to store my photos and view them anytime, I am better off running it on a Tailscale network that only I (and some friends/family) can acces, no reason to expose it publicly and then try to secure it.