Silly suggestion, and no idea if it will work, but it’s an easy one to test;
Get some cooking/vegetable oil, and see if it will help dissolve the residue by putting a bit on some kitchen towel and either scrubbing with the oiled paper towel or leaving that towel on the residue for 10 mins and seeing if the grease has softened.
If the oil does seem to dissolve/soften the grease residue then you can add some bicarb/salt to act as gentle abrasive as it won’t dissolve in the oil as it would do in water
I’ve used cooking oil to dissolve tar/bitumen paint from my skin and clothes before and you can then use soap to clear the dissolved tar in oil.
Otherwise use a kitchen degreaser like you’d clean a traditional oven with.
I imagine what’s happening with the oil is something akin to polymerization, so you either need to break the polymers bonds or dissolve in a suitable solvent
I’ve run into this problem also with both a 2.4Ghz mouse and a 2.4Ghz mouse and keyboard combo, never really quite realised that it was to do with the hub, but had clocked that an extension lead corrects it for some reason!
Thank for pointing this out as it means I actually know to put the dongles on extension leads, I always thought it was something to do with a weird grounding issue on a cheap hub or something