In August 2018 Ebay seller andryushyk from Kyiv in Ukraine was trying to sell these fake Belgian plates. In all fairness he is selling them cheaply but he does not say that they are fakes.
If you look at other Belgian plates on here (type Belgium in the search box on the photos page) you will see that the officially issued Belgium rear plates have the CV seal on them. These plates have the wrong seal and the wrong etchings and watermarks and are not official plates. If they were genuine, it would be illegal to even own them in Belgium.
If you do not know exactly what you are bidding on or trading for, check very carefully as even sellers of many, many genuine plates sometimes get fakes.
Buying fakes like these means you will end up with very overpriced scrap aluminium in your collection.