hello,
I have similar issue with my 75k km F. Ka.
Once I switched to winter slicks I don't have any more wheel sounds inside so I hear clear whine of diff:
while accelarating
while using engine as break (deccel)

there's just some sound from clutch bearing, its well-worn but not grinding yet, so that is not the issue.

I took my old man (he is car technician for all the time I know him ) to have a ride with me and he said that for this small car with FWD it's nothing weird: gearbox is slightly used, so it will whine. But no problems with bearings, that should be different sound (rumble, grinding etc.)
I remember this type of sound from homebuilt tractor, very common differential whine, nothing bad. (Wheels/axles just doesn't fit perfectly anymore to each other, causing some forces to bend the axles, causing extra friction etc).
but that is very imho... I am not expert at all.