Personally I find that law stupid for many reasons. Where do I begin... Your ISP may reuse IP address range or put you behind NAT/proxy. You can use multitude of VPN services, TOR circuits or even your neighbour's wifi to access our site, so "your" IP address is poor source of identification. Same thing for HTTP headers, including Cookies. You can install whatever browser extension to fake, delete and/or play with them and confuse anything I might have on server side.
Seriously, if you'd put couple of hours into learning how HTTP works, you'd be more educated than "geniuses" that put GDPR into law. The electricity spent on you reading this page probably did cost a life of few trees, so bravo lawmakers! Such privacy protection!
Po polsku: użyj google translate.