I think GP is pretty clearly implying more akin to Prop 13 but for renters (i.e. Prop 13 locks in increase in property taxes to 2% a year), this policy would do something similar for rent.

It benefits existing renters because new entrants (new renters) would have to pay market price, but existing renters might be behind market rent if market rents are increasing too quickly. Same way that Prop 13 works.

Dynamic in the sense that it's not fixed at 2% but tied to some sort of variable index (San Diego for example does CPI + 5% with a hard cap of 10% YoY increase I believe)

> I think GP is pretty clearly implying more akin to Prop 13 but for renters (i.e. Prop 13 locks in increase in property taxes to 2% a year), this policy would do something similar for rent.

It's called rent control. That's literally describing the existing rent control policies in SF: rent is fixes save for an extremely minor increase around 2%. Allowing a fixed price increase is still a form of price controls.

I really want the previous comment to elaborate on this:

> existing tenants win vs potential new market entrants