What you are doing is just good business. You are not implicitly or explicitly colluding with other property owners to set you prices. You are simply doing market research based on publicly available data and making an independent decision.

Contrast this with a cartel that includes a significant number of landlords in your city (i.e. way more than just a couple of your buddies) that (1) shares non public info such as current occupancy rates, current lease terms and durations, etc., (2) sets prices as a bloc, and (3) enforces compliance on pricing targets.

It’s qualitatively different from how you described your situation.