Web config letsencrypt request uses mycloud.ownyourbits.com instead of my domain

Nextcloud version
Operating system and version nextcloudpi v0.62.6

I’m using the web interface of the configuration (:4443) to get a letsencrypt certificate

providing my domain (which is NOT “mycloud.ownyourbits”), email and username in the text boxes

I get an error message that looks to me as if not my domain but the example domain “mycloud.ownyourbits” is used for the request - and therefore the challenges are failing.

What’s going wrong there?
Any help would be appreciated

This is the log I see in the web config:

[ letsencrypt ]

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for mycloud.ownyourbits.com
Using the webroot path /var/www/nextcloud for all unmatched domains.
Waiting for verification...
Cleaning up challenges
Failed authorization procedure. mycloud.ownyourbits.com (http-01): urn:acme:error:dns :: DNS problem: NXDOMAIN looking up A for mycloud.ownyourbits.com
- The following errors were reported by the server:

Domain: mycloud.ownyourbits.com
Type: None
Detail: DNS problem: NXDOMAIN looking up A for