If you do not trust Tailscale as a company, here is an open source re-implementation of the server called headscale. Some/all clients are open source as well. So, you can review all components yourself or pay for a professional third-party review. Otherwise, if you take a binary blob from any origin, including Tailscale, and have it run with privileges on your server, there are few limits on what this blob can do. Yes, backdoors are technically possible, but probably bad for Tailscale’s business if that ever came to light.
Naja, da an unbekanntem Ort in der Cloud gehostet nur eingeschänkt nutzbar für personenbezogene oder vertrauliche Inhalte (also fast alles bei firmenbezogene Videogespräche). Aber immerhin, nettes Produkt, würde sowas gerne als Open Source zum selberhosten oder bei vertrauenswürdigem Anbieter sehen.