A bunch of landlords all use the same software to tell them how to price rents. The software continually pushes prices higher and higher. The software requires landlords to use their pricing as a condition of use. Now you have a price-fixing cartel for rent.

https://en.wikipedia.org/wiki/Price_fixing#:~:text=Rent%20al...

Like "price fixing". Landlords illegally colluding to artificially inflate the price of housing.