It’s actually quite common now. If someone isn’t wearing a shoe conducive to squatting they’ll go shoeless. Running shoes and basketball shoes are terrible for squatting (more so when you start going up in weight), there’s too much cushion and padding in them.

Btw, if you don’t want to pay $150 or more (they can get pricey) for a good powerlifting shoe, vans, converse, or a wrestling shoe are a decent replacement.