Looks like its wet.
Clean that up as soon as possible. Pull the vinyl flooring up and get all of it dry. Then use some brake cleaner on a cloth to try to ge tthe residue. Brake fluid (except silicone DOT 5) will damage or remove paint. Rubber isn't bothered by it.
Before concluding this is the problem, look at the brake hoses for both calipers. Make sure neither is leaking.