Any UBI that avoids people getting poor will have to come mainly form taxes, and will mostly not make any bit of inflation.

The typical answer is "printing money causes inflation", but in the context of this feedback loop, it only causes exactly as much inflation as is required to cancel out the deflation caused by automation-induced layoffs and productivity increases. That's the magic of feedback.

But if it's because the resulting UBI would still be insufficient for welfare, we could also use taxes to fund a secondary "revenue-neutral" layer of UBI that taxes the rich and redistributes to everybody, but probably it makes sense to go in slower steps, seeing what level the primary UBI stabilizes at and then adding a secondary tax-funded one if the primary one isn't sufficient for both welfare and sustaining economic demand.

(The secondary UBI would probably still be somewhat inflationary, even though it's funded by taxes, just because poor people spend more of their money on things that are highly-weighted in the CPI, but the feedback loop will balance that out).