It's nice to present a clean (modeled) plan, but it's something different when it hits reality. Social security now, is what UBI will look like a few decades down the road.
Somebody will find a way to exploit UBI and that hole gets patched, then there's another patch and another. Not to speak of how different political ideologies will apply their own modifications to previously established laws
Will residents without citizenship receive the UBI? If yes, how long do they have to reside to be eligible? Will expats with citizenship receive the UBI? Will children receive the full UBI starting at birth? If not, when will they? Is it an abrupt step (if yes, at what age?), or is it gradual?
There are many subtleties to the meaning of "universal". And that's just what I've come up with in 2 minutes...
Also, I would recommend to read "Debunking Utopia" about the social system Nordic countries implemented in the past, some kind of model for solving the problem of living decently for people without possibilities and/or problems to make a living. The countries are slowly but steady reducing that system because it solves nothing and creates extra problems. With UBI, which is a bigger plan than the system Nordic countries had, you would end up with the same if not worse problems than they faced: people decide not to work for low wages or in jobs that are needed but unappealing (and I don't blame them, for sure), but because someone has to do the jobs, wages increase a lot, which in turn, increases the costs and price of those services. And, voila, we are at the beginning of the problem, were people are stressed or unhappy because they have to keep jobs they don't enjoy or like.
The difference is that the UBI would be the new penny, because you could not buy anything. Maybe with AI and automation we would get there, as robots would not complain or care.