Apex domains cannot have CNAME records.
Question and response
Question
dig polygen.com.pl. NS
Answer
polygen.com.pl. 2 NS dns100.ovh.net.
polygen.com.pl. 2 NS ns100.ovh.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0