The common brimstone Gonepteryx rhamni
https://www.inaturalist.org/observations/97378354
As the name implies, it is a fairly common butterfly.
But they are beautiful and so I have chosen one good photo for your enjoyment.
camera Pentax KP
lens HD PENTAX-DA 55-300mm F4.5-6.3 ED PLM WR RE
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both wings really look like leaves
The butterfly has great camouflage. If I saw it from a distance, I certainly wouldn't be able to recognize it.
The wings of butterflies are very similar to leaves. This is good photography.