Signal, I agree... it has flags for me in so many ways.

Tor. Unlikely though. For sure many nodes are controlled and now they are using massive power to unlock the traffic, but was not set up as a honeypot per se, it is now, probably, technologically quite compromised though.

Mullvad. Funny, your suspicions probably got enhanced when Mullvad makes a browser based on Tor's. But I still not highly suspect of Mullvad. Quite steady organic growth, profitable, no much pronouncements or catering to certain "targeted" groups... No mayor red flags for me.