We have published in Partner Center - Marketplace Offer - Azure Application.
It is used by end-customer from Azure marketplace.
What nobody knows, is how this can be upgraded, instead of deleting the customer instance app and database data, to install again with newer version.

The marketplace offer is updated and contains the newer version.

We are constantly juggling between Partner Center - Marketplace support, and Azure Technical support. Nobody knows, how to (end-customer) update the existing partner Azure app to a newer version, docs is not clear. Who to contact?