Nah, UBI done properly would claw back excess wealth from those who don’t need it and increase spending at the bottom on essentials. And besides isn’t the entire point of capitalism that that sort of price fixing isn’t possible?
Putting money into the working classes won’t be inflationary, unless you think they already meet all their basic needs.
I' not convinced it won't have an inflationary effect. If capitalism worked properly we wouldn't need the likes of OFCOM, OFGEM to step in would we? Since we've brought the free market into a number of services we've not seen price increases stagnate or slow down.
Plus it's universal - everyone gets it regardless of wealth and income. It would be 'worth' more proportionally to the poorer but it's still not clawing back excess wealth.
You could have the argument that if this replaces the PA then those with higher incomes end up paying more tax which does that but when you take into account the effective tax rates of the very wealthy who can access tax havens and top accountants the larger burden will be on the middle. So you might close the gap between the poor and the middle but pushing the poor up slightly and the middle down, but the wealthy are relatively unscathed and the main issue with wealth disparity gets worse.
I don't think it's necessarily a bad idea or any worse than what we do now, but I don't think it's going to be this great solution some seem to think it will be. Minimum/Living wage was supposed to be a big leveller and its effect has been minimal. More people requiring food banks etc than ever before.