Have you tried focused steam - not a steam mop - but a steam of steam focused on the area?

What products have you tried? It seems that soap scum or water hardness must be what sticks stubble to the floor. There are several products to fix either. Have you tried scrubbing pads like a Dobby pad? Some combination of removers and scrubbers should fix your problem easily.

What is the floor made of? Fiberglass? Tile? Something else?

I had to buy one of those deck brushes from Lowes. It works like a charm!

My goto for stubborn bathroom and kitchen deposits and films is EasyOff Fume Free. It is very powerful but safe for most plastics and porcelain surfaces. Spray it on; wait an hour; wipe it and the gunk off with a wet rag.

I would just use Dawn dishwashing detergent full strength, brush it on, let it set for a while and it will dissolve whatever is adhering the stubble to the floor.