background requests with wrong protocol if config-"url" and acutal request mismatch / trust_x_forwarded_proto config value is ignored about pretix HOT 1 CLOSED

Unfortunately, this situation will not be fixable and I must consider it an unsupported configuration. Even though it would be possible to fix your specific issue at hand with great effort, other issues along the same lines would not be fixable.

pretix needs to be able to generate URLs outside of the request cycle. An example would be if a waiting list user is informed, we need to generate a link to the ticket shop, even though we have no current HTTP request. Without a current HTTP request, X-Forwarded-Proto is not an available source for which scheme to use. We therefore look at the scheme of the global URL to figure out if this installation supports HTTPS.

The only way out would be to find a way to set a HTTPS URL in your url= parameter. I have personally not yet seen a setup where that is not possible.

from pretix.