Law / Tax in Poland? [57]

Do you know this website? calculatenetsalary.com/calculate-net-salary-in-poland.html

Do you think it calculates it properly??
I tried with a gross salary of 3000zl/month, it says the net salary would be 1863.91zl/month, which means 38% of taxes a month!! For a low salary!

Well, for what you've said in the previous posts it seems absurd... Isn't it???