@HibiscusKazeneko would you mind sharing which country you are in? Qobuz is known to act strangely when accessing releases in countries where it is not available.
ECAU uses the Qobuz API to check whether there are “goodies”, like digital booklets, available for download. My best guess is that this request is causing the 403 error. If the API request fails, ECAU uses a fallback solution that does not rely on the API. However, this is only triggered on 404 errors, not on 403. I can change it to also use the fallback option on 403 errors, but ideally I’d like to know more about why it is returning a 403 in the first place, so we might be able to find a better solution.