u/Strong_Zucchini5443

I am going through a big batch of mixed stamps I bought from a flea market, but this one has me stumped. There is no year, country or value on it, the back is also completely white. It's made from some thicker paper and feels like a magazine cover (so I think it must be newer also bc of the print quality). I tried researching but nothing comes up except that it could be a test print or something similar. Does anyone have any ideas?

Dimensions are 3.5 x 1.8 cm