recently updated the NS records for my domain through my registrar, and after verifying on dnschecker org that the NS records are properly set up, I noticed that Cloudflare has not yet recognized the changes made through propagation.
Adding your domain to Cloudflare does not involve creating NS records. You need to change your assigned nameservers at your domain registrar which is something entirely different.
You might check the provider-specific instructions in the document below to see if there are more explicit details on how to accomplish this at your registrar.