Does anyone know what kind of mold/fungus this is? And is it harmful to the plant?

I just potted a couple new petunia plants and Firefly petunia seedlings in Miracle Gro Potting Mix and 3 days later this mold/fungus appeared in all of them. I’m not too worried about my larger plants, but I’m worried that it’s going to kill my Firefly petunia seedlings.

I can’t figure out what it is since a lot of the pics of mold/fungus online don’t look like this. I’m pretty sure it was the potting mix that was the culprit since this mold/fungus has only affected the pots that I used that particular potting mix in. (As in, every single pot I used that mix in grew the mold/fungus. And the other pots that I planted on the exact same day and used a different mix for don’t have it.)

I’m also scared to spray any chemicals to kill it because I’m scared my seedlings aren’t old enough to handle it yet.

Any thoughts on what this could be?