Resolving "unable to create / renew a HTTPS certificate"

I logged into the website for Irvine Project Masters #3672902 as administrator in order to update the website, and saw a warning message: "[2022-05-28 08:12:06 GMT, FreeToastHost System Warning]  *** IMPORTANT! ***

NOTE:  We were unable to create / renew a HTTPS certificate for your custom domain: www.irvinepm.org
This means that you may not be able to access your website using https:// with your custom domain 
name after any existing certificates expire."

I confirmed that our custom domain has NOT expired. ( www.godaddy.com/whois/results.aspx?check...&domain=irvinepm.org indicates that it will not expire for more than a year.) I am not aware that we use domain forwarding. 

www.digwebinterface.com/?hostnames=www.i...ns=auth&nameservers=
reports;; Truncated, retrying in TCP mode.
[url=javascript:addhost('www.irvinepm.org.')] www.irvinepm.org .[/url] 3600 IN CNAME [url=javascript:addhost('irvinepm.org.')]irvinepm.org.[/url]
[url=javascript:addhost('irvinepm.org.')]irvinepm.org.[/url] 3600 IN NS [url=javascript:addns('ns18.domaincontrol.com.')]ns18.domaincontrol.com.[/url]
[url=javascript:addhost('irvinepm.org.')]irvinepm.org.[/url] 3600 IN NS [url=javascript:addns('ns17.domaincontrol.com.')]ns17.domaincontrol.com.[/url]

To me, this doesn't indicate any obvious thing that would cause the reported problem.

Can you please advise on what further diagnostics I can try that would determine why this failure occurred, so that "Note that the system may remove your custom domain from the database to prevent further invalid attempts at cert renewals." doesn't happen? Because as it stands, I don't see anything obvious that I can fix.

Thanks!

The certificates are renewed before their expiry date.  Yours failed on 28 May, but it was been successful in the subsequent run, so no action is required.
The certification is provided as a service to clubs using custom domains for their FTH sites.