I know someone who live in subsidized housing. I understand this is not a common situation so it's not representative of a lot. Her rent is literally defined as a percentage of her income. She doesn't work, so income is in part child support payments and who knows what else. I believe the percentage is over 30, so if you handed her UBI over $300 would go straight to her rent.
Prices are like that - hand people (actually loan them beyond their means) money to go to college and tuition skyrockets. Give them heath insurance and those costs go up. Hand them a blank check every month and it will most likely all go to some form of inflation.