The result of playing with the "Fascist EU" concept. Needless to say, this is not intended as Fascist nor Nazi apologism.
There's no coherent explaination for this, as the very existence of Poland, Czechoslovakia and Austria can illustrate. It's a reflection on how would it be if the Nazi roundel-like pattern was as common as the tricolour pattern is IOTL. Also, the Europe of the Peoples, with a dark twist.