Hello, this is not paint but anodising (a coloured oxide layer formed on the surface of aluminium). For the last 1 month there has been nothing to report in terms of wear on mine. However, anodising doesn't like knocks, so you have to place the magnetic connector carefully, otherwise it will knock and damage the oxide layer. Note that grey Macbooks also have anodising (but neutral, without colour), but the impact is less visible because the aluminium is the same colour as the anodising, so the resistance is the same between grey and black.

Nothing has flaked off on my device yet.