UBI is implemented tomorrow. Every citizen gets $1000 per month.
Landlord now knows you have an extra $1000 that you never had before.
Why wouldn't the landlord raise prices?
Now you have an extra $1000 a month and instead of eating rice and beans for a few meals you go out to a restaurant. The restaurant owners know everyone is eating out more so why not raise prices and maximize shareholder profit as always. The restaurant/corporation is on TV saying, "well, demand increased and it is a simple Economic principle that prices had to increase. There's nothing we can do about it".
Your state/country has toll roads. The state needs money for its deficit.
UBI is implemented and the state/country sees it as the perfect time to incrementally raise toll prices.
Next thing you know UBI is effectively gone because everything costs more and billionaires keep hitting higher and higher all time net worth records.
If there was no external stimulus, they would have a slam dunk case. When every gas station jacks the price up 20 cents because the price of oil goes up, it's just the market.
Put 1000 dollars in everyone's pocket, every (smart) landlord will react and change their prices accordingly. That's not "Collusion", and the DoJ will never be able to make a case. That's just landlords paying attention to what happened in the world.
The external stimulus you're looking for there is the cost of gas to the gas station actually rises. There is no extra cost to landlords. Raising prices in concert with your competition with no reason is the definition of collusion.
That's not a reason. There's not a carve out in collusion for, "median pay increased". Reasons are cost push. Which is why corporations spent so much time trying to blame inflation on the pandemic and supply shortages long after those matters were cleared up.