What Psiphon's terms say
Psiphon's terms of service and privacy policy have 9 rated points: 1 serious, 4 bad, 2 worth knowing and 2 good. 9 apply whenever you use the site, signed in or not; 0 only once you have an account.
Whenever you use Psiphon
Serious 1
Your browsing history can be viewed by the service
Your browsing history can be viewed and analyzed by the service
Where it says this ↗
Bad 4
Third-party cookies are used for statistics
Where it says this ↗You are tracked via web beacons, tracking pixels, browser fingerprinting, and/or device fingerprinting
Where it says this ↗Third-party cookies are used for advertising
Where it says this ↗Many third parties are involved in operating the service
Where it says this ↗
Worth knowing 2
Only aggregate data is given to third parties
Where it says this ↗This service gives your personal data to third parties involved in its operation
Where it says this ↗
Good 2
Location data will not be collected, used or shared
This service does not collect, use, or share location data
Where it says this ↗Logs are deleted after a finite period of time
Where it says this ↗
If you have a Psiphon account
No account-only points rated.
The documents
Ratings by ToS;DR volunteers; they can lag behind the current terms. Not legal advice.