There were three projects designed by KSUS and BBTBr.Panc. and PZInż which even managed to build a wooden model of it. The name 20/25TP is not official. It was created by Janusz Magunski analogously to nomenclature used for other Polish tanks of that period. According to different classification it could be medium tank or heavy tank.
You can download the paper model template here: 20/25TP Polish Concept Medium Tank Free Paper Model Download