Wow, what a fantastic photo! It’s so neat to see spiders from all around the world; thank you for sharing!
This looks like a male crab spider (Family Thomisidae). I’m thinking he may be Ozyptila scabricula.
iNaturalist observation of Ozyptila scabricula, female:
Website listing spiders of Europe, from which I found Ozyptila scabricula listed as occurring in Poland:
What do you think?