Tailscale is a userland process built in a memory-safe language, which leaves you only the SSH protocol cryptography-type vulnerabilities, which are themselves mooted by Tailscale (see downthread for a discussion about why they didn't simply expose rsh instead of ssh).

This is safer than OpenSSH.

(OpenSSH, as a piece of software, is extraordinarily safe, and has one of the best records of any memory-unsafe codebases. But OpenSSH as configurable infrastructure is much less safe; people screw it up all the time.)