Apex domains cannot have CNAME records.
Question and response
Question
dig groupflow.app. NS
Answer
groupflow.app. 2 NS ns2.groupflow.app.
groupflow.app. 2 NS ns1.groupflow.app.
groupflow.app. 2 NS ns3.groupflow.app.
Authority
The response has no authority records.
Additional
ns1.groupflow.app. 2 A 134.199.180.63
ns2.groupflow.app. 2 A 104.248.110.33
ns3.groupflow.app. 2 A 152.42.149.94
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0