UBI as a concept does not add up. It assumes an even production of all goods that people might need, but there isn't, you are giving everyone fiat currency that is not inherently tied to any physical good. Very fast you will descend into either plan economy where you get food stamps, or an economy where people are trading goods that are actually tied to value.

For example, you go to the store to get eggs, since everyone has UBI, they decide to also get eggs, the eggs either run out, or the store raises the price, at which either you will get food queues like in the USSR, or everyone will need more UBI to afford eggs. The solution to this is to increase egg production, but this is not instant, and not necessarily a priority, while money transfers are instant.