Excuse me being naive but why? It would be a unique situation and as such any predictions of what's gonna happen are purely hypothetical.
Your last point is kind of moot as it could be used to argue against any kind of wage or income increase for poor and middle class "They just all gonna spend it paying their landlords".
If the basic income accounts for "average living costs" then ideally the average rent should be calculated too and factored into it, so landlords can't just jack up rents and expect their tenants to "reach through" their UBI.
A UBI would give the poor and middle class at least some bargaining power with employers, that's already progress. The whole situation about affordable living space becoming rarer and protection of tenants are valid concerns, but you can't expect a UBI to fix everything, different issues need different approaches and solutions.