You're right, the problem in the US was multi-causal. I mention that case because it is probably the best large-scale deployment of a UBI-like program any country has ever done.
While we can't completely untangle the exact contribution magnitude, I think we can deduce that at least some meaningful % of the shortage/inflation situation was caused by the UBI-like program.
I would agree with that. I wish there was a way to know how much though. There was an undeniable impact of giving people “free money,” but it doesn’t seem like most Americans received very much. Most of the people I know of received their 2-3 checks and that’s it. You’d see news articles two years into the pandemic saying things like “Americans finally running out of stimulus money.” It made me laugh because it seemed like most people spent that money crazy fast on their bills and very few people were able to actually pocket that cash.
It was the people working close to minimum wage that were most affected - it was common to see small business owners unable to get workers to return because these payments were higher than they were making on the job.
I think this would be the most likely outcome: basic income means no longer needing to work, and even if it just covers the essentials I think a lot more people are going to go that route than most expect.
While we can't completely untangle the exact contribution magnitude, I think we can deduce that at least some meaningful % of the shortage/inflation situation was caused by the UBI-like program.