IE like Crypto AG:
In 2020, it was revealed that the Swiss company, Crypto AG, which provided secure communications services to ~120 governments throughout the 20th century, was secretly ran by the CIA and West German Intelligence. The CIA and later NSA were able to read encrypted communications for many countries such as Saudi Arabia, Iran, Italy, Indonesia, Iraq, Libya, Jordan and South Korea.
they were talking about proxy VPNs, whereas tailscale is for building actual virtual networks to connect your devices, which is a completely different thing (besides sharing the same approval foundation).
If you were to distrust tailscale (and you’re not simply self hosting headscale), an attacker might be able to access for otherwise non-public devices(’ ports), reroute/MitM your traffic and monitor which device connects to which.