Hmm. 10 years ago the surgeon gave you 20 years, probably based on mortality data that was already 20 years old at the time.

Prostate-cancer treatment has changed so much since the 1990s that data collected back then (even if cited in recent studies) doesn't tell us much.

There’s really no way to know…so much depends on your post op pathology (Gleason, etc). But if you’ve been good for 10 yrs post op, even IF you had a recurrence, your cancer is most likely a slow growing one and treatment ( or not) would depend on your age, physical health, etc…

Here's a tool you can use to find your statistical risk of recurrence based on pre-op PSA, Gleason score, and basic path finding (cancer confined to prostate vs not). It only goes up to 10 years.
https://www.hopkinsmedicine.org/brady-urology-institute/conditions-and-treatments/prostate-cancer/risk-assessment-tools/han-tables
Of course, statistical risk is not the same as personal risk. It only means that, of 100 men with findings like yours, how many will have a return of the cancer (usually measured as a rising PSA). No one can tell you what will happen to you as an individual.