Apex domains cannot have CNAME records.
Question and response
Question
dig trustpilotservice.com. NS
Answer
trustpilotservice.com. 5 NS ns-481.awsdns-60.com.
trustpilotservice.com. 5 NS ns-1886.awsdns-43.co.uk.
trustpilotservice.com. 5 NS ns-1220.awsdns-24.org.
trustpilotservice.com. 5 NS ns-630.awsdns-14.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0