Custom Hostname - Domain Verification GoDaddy, Namecheap

[juljo]

We have a SaaS product and our users add their domains in our platform using Customnames, to verify the domains we use the CNAME and TXT records provided by cloudflare. The domains get successfully verified but when using that domain to serve a static site I get this error: ‘DNS_PROBE_FINISHED_NXDOMAIN’. I’ve contacted godaddy support and they told me that I should add an A record with the hosts IP address.
Anyone has faced this issue and if so, what is the solution?

[Laudian]

Could you maybe share the your customers domain and the subdomain used for the CNAME?

[juljo]

https://landerlabpages.xyz
This is a domain from godaddy, I contacted their support they gave me this link: https://www.who-hosts-this.com/?s=landerlabpages.xyz

Here I took the IP address and added it as A record and it works for the moment. The question is, would this domain work permamently?
I also added a subdomain: http://lp.landerlabpages.xyz/ here I get this: lp.landerlabpages.xyz s server IP address could not be found.