Looks like XPS 2 stroke oil sitting on top of a little water. I would inspect your small oil lines or change them if they are original, inspect the entire oil system looking for leaks or damage. If you clean the hull up good and then put some paper towels or shop towels beneath the oil tank that can help find the leak. Or maybe there was some oil spilled while filling the oil tank, it doesn’t take much oil to look like a lot of oil when it’s floating on water