Crusty stuff coming up between basement floor planks
Some vinyl planking, like mine, has a thin layer of corkboard on bottom to help padding.
This is why orange-brown crust is seeping up. Moisture from slab is pushing thru the cork layer and forcing it up. In my case, just in very heavily traveled area in front of bar.
Just scraped mine up with plastic dish scrubber and put some lemon oil on it after.
Lasted 3 months and had to do it again. Cheaper than getting new floor!