That domain is configured to use Vercel DNS, not Netlify:
% dig olawaleyusuf.com NS +noall +answer
; <<>> DiG 9.10.6 <<>> olawaleyusuf.com NS +noall +answer
;; global options: +cmd
olawaleyusuf.com. 86400 IN NS ns1.vercel-dns.com.
olawaleyusuf.com. 86400 IN NS ns2.vercel-dns.com.
However it also seems you have configured Netlify DNS (note the last line)
% dig olawaleyusuf.com NS +trace | tail -n 6
;; Received 683 bytes from 192.52.178.30#53(k.gtld-servers.net) in 170 ms
olawaleyusuf.com. 86400 IN NS ns1.vercel-dns.com.
olawaleyusuf.com. 86400 IN NS ns2.vercel-dns.com.
;; Received 92 bytes from 198.51.45.5#53(dns2.p05.nsone.net) in 26 ms
Edit
I can see using DNS Checker (see here) that some regions are showing Netlify DNS, others Vercel.
If you have recently started the process of switching from Vercel to Netlify, do note that propagation can take up to 48 hours.
See this thread for more resources specifc to domains