Apex domains cannot have CNAME records.
Question and response
Question
dig myhero-academia-merch.com. NS
Answer
myhero-academia-merch.com. 5 NS ns-1942.awsdns-50.co.uk.
myhero-academia-merch.com. 5 NS ns-1185.awsdns-20.org.
myhero-academia-merch.com. 5 NS ns-213.awsdns-26.com.
myhero-academia-merch.com. 5 NS ns-1002.awsdns-61.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0