Fullcalendar View module maintainer sells new versions of the module

Problem/Motivation

The maintainer of Fullcalendar View module, mingsong → , sells the newer version of the module, and rejects community patches to update the module to work with the newer version of the library. I don't think that this is compatible with Drupal's licensing.

Steps to reproduce

Here the maintainer advertises the premium version of the module: https://www.drupal.org/project/fullcalendar_view/issues/3466648 🌱 Premium Version Active

Here rejects, closes, an issue about updating the module to work with the newer version of the library:
https://www.drupal.org/project/fullcalendar_view/issues/3399885#comment-... 📌 Update to Fullcalendar library v6 Needs review

Proposed resolution

Maintainer should accept patches to update the module. It's up to the maintainer himself if he wants to share his premium version, however he cannot block patches if community provides patches.