Nobita,
I’ve seen this on a handful of mice and my Logitech (slightly different model) is starting to do something similar. I haven’t done this yet, but I’m wondering if you can just find the right high-quality tape and cover it up? It won’t look as good, but might be quite functional and only cost you a dime every few months and make it last a whole lot longer. I’m thinking maybe fabric tape? I’m sorry if this isn’t what you hoped but thought it might be a decent idea.