Of course UBI will create new money - how else are you going to finance it? Giving each adult American $1000 per month would cost at least $2.5 trillion. Let's assume that UBI replaces all other Social Security spending - that's currently $1.2T, so you are still $1.3T short. You cannot collect that much in new taxes.

Even assuming that you somehow manage to finance UBI with tax raises alone think about what you'll be doing: you would be moving money from the rich to the poor, which sounds good in theory, until you realize that rich people and corporations keep their money in financial assets. Now, the reason why all the FED money printing so far caused only mild inflation is because the money flew to financial markets. If you use taxes to redirect it to common people then you are doubly screwing them: you are crashing stock markets, ruining their 401(k) savings, and at the same time causing price inflation of everyday things.