App verification does not work when eTLD not in publicsuffixlist

[langurmonkey]

My app uses an App ID that contains a domain and a subdomain (de.uni_heidelberg.zah.GaiaSky), but when I start the verification process the subdomain seems to be ignored:

Verify your app ID to indicate that your Flathub upload is approved by the app developer. You'll need to prove that you have control of the app via a website on the app's domain or by checking access to the app's account on a source code hosting site. The verified badge will be shown alongside the app name, publisher name, and the way that the app ID was verified.
Create a page at https://uni-heidelberg.de/.well-known/org.flathub.VerifiedApps.txt containing the following token:

Obviously, I don't control uni-heidelberg.de.

I've followed flathub/flathub#4943 and #3259 (both fixed), but the fix seems to work only for suffixes in a PSL, so arbitrary subdomains in the App ID are not really included.
Should this be working with subdomains also? If not, is there a way to have it verified manually?

More context: flathub/de.uni_heidelberg.zah.GaiaSky#57

[bbhtt]

The problem seems to be that uni-heidelberg.de is not in public suffix list https://publicsuffix.org/list/public_suffix_list.dat, so the library being used to calculate the domain for verification is returning the toplevel uni-heidelberg.de instead of zah.uni-heidelberg.de

[bbhtt]

The owner of uni-heidelberg.de can submit it to PSL https://publicsuffix.org/submit/ then supposedly it should return the correct domain.

[langurmonkey]

The owner of uni-heidelberg.de can submit it to PSL https://publicsuffix.org/submit/ then supposedly it should return the correct domain.

I'm afraid this is not gonna happen, unfortunately. I'll try to contact the university computing center, but in the case of a negative answer, would it be possible to verify manually?

[bbhtt]

It's possible yes, but there are some other apps affected too whose top level domain is not in PSL

[langurmonkey]

Should I send an email to the admins to get verified manually, as suggested in the docs?