Polen, Woiwodschaft Großpolen, Pila (Schneidemühl), Wald in dem Naturschutzgebiet Kuznik, 60 m, 25. Mai 2017 (Freilandfoto: Marek Idec)
I think it's likely Cyclophora punctaria. You can possibly recognize that it's on an oak leaf on my photo. Actually on the underside of the oak leaf.
Please, confirm I'm not mistaken.