Axles and bearings don’t get flat spots from sitting. That’s not even a thing. Now, tires can get flat spots from sitting.
Axles and bearings might get rusty spots, depending on how well they’re greased and the climate in your location and the cars level of exposure to moisture. Can happen on ring gears too, the “high” parts can develop rust since the oil all sits down low. If nothing moves then the oil doesn’t get stirred up and the gear and bearings don’t make a pass through the oil to keep the rust away.