There is a very big difference between the two. A payroll tax won't help people who can't work right now who do live paycheck to paycheck, because they aren't getting any hours right now. A UBI will.
As for the inflation issues, the problem is that inflation didn't come with anything good, so it was all bad. Let me explain.
Almost all recessions are caused by a demand shock, where people stop buying as much as they used to. This includes the Great Depression, the great recession, dot-com bubble, etc. Basically, a bunch of companies go belly up and people are scared they will lose their jobs, so stop spending, creating an excess supply. The solution, using Keynesian economics, is for the government to spend instead of the people, and buy up the excess supply.
But we aren't in a demand shock, but a supply shock. In a supply shock, the entire economy stops producing as much as it used to because there is some disruption in the supply chain. In the 70s, it was the Oil Embargo. Now, it's corona stopping people from working. If the government tries to buy it's way out of the recession using Keynesian economics, there isn't an excess supply for them to buy, there's a supply shortage. So there's nothing extra for them to buy, so when they buy stuff, the supply shortage gets even worse. This is what happened during the oil embargo, as the Fed had no idea this was a thing and acted like it was a normal recession. This helped no one, and lead to high, sudden inflation. This high, sudden inflation is killer to banks as suddenly mortgages earning 3% a year are inflating away at 8%, and lead to thousands of banks going bankrupt. And those banks offering loans is what is going to keep many companies in business during this time.
tl;dr: When I warn of inflation, I'm not going all Austrian Economics in a crisis. I'm trying to people advocating we shoot ourselves in the foot when we need to be running.
