How to clean AirPod max headband? (not the fabric part)

I bought my daughter a new AirPod Max. She put it in her bag, and surprisingly, the AirPod headband got strange brown color, probably from her bag?

The AirPods were in the case, so the cushions are ok. however, the headband has no protection, thus it was exposed.

Any idea how to clean it?

Note that the headband is made of 2 materials: Mesh fabric and some sort of silicone (?). The fabric is ok, but the strange color is on the silicone part.

We couldn't find instructions on Apple website (only related to fabric cleaning).

BTW, we went to an Apple store to ask about it, and even there - they didn't know and didn't offer any support. I must say that I'm greatly disappointed at Apple support.