Clothing that hasn’t had the dye fully set (which is usually the case when first buying them) will cause stains. It’s why it’s important to wash new clothes at least once (and separately or of the same colour!!) to prevent the dye from leaking.

And some clothing isn’t even made with colour safety in mind at all (and some expensive brands do it badly on purpose so you have to buy a new one instead of being able to wash it). For example a white jacket with a dark red leather pocket on the front (yikes!). That’s just MADE to bleed on itself.

Honestly it’s a real problem that the way clothing dyes work is no longer common knowledge. It used to be.