It might discourage people from protesting who hadn't protested so far but for any who already protested, losing UBI would mean they've now got nothing to lose and would therefore become completely unmanageable. So, shutting off UBI is actually a very bad idea for controlling people. You'll piss off a) the people whose UBI you shut off and b) all the people who care about those people whose UBIs got shut off.
The result is that the people will be seething with rage but can't show it publicly. I don't think I need to tell you the result. It won't end pretty. You really need to think about what power is and where a government gets it's power from.
You know, if you just give everyone 20% more money, without anything else changing, the end result will be that prices go up 20% and no-one is any richer in any practical sense. You merely created instantaneous 20% inflation. People might fall for this once. Although I doubt it.
If you actually increased the production of the things that people want by 20%, that'd work, even without any increases to the UBI. The prices would just fall by 20% and everyone would be 20% richer compared to before. However, this won't be quite that simple. If it was, it'd have already been done.
You really should try to get a working understanding of economics and politics and power before you try to thinking about things like these.