@maperal @demoakracia @victorhck
Al parecer, en el caso de Gimp es una operación bastante opaca en la que te lo presentan como "de oferta", mientras que en el caso de Krita es una proposición de los propios desarrolladores que piden que les eches una mano:

If you buy Krita in the Windows store, you will support the development of Krita directly: currently, two volunteers from the Krita community are sponsored to work full-time on Krita. You will also have the convenience of easy installation on all your Windows devices and automatic updates when a new version is released. By buying Krita in the Windows Store you support the development of Krita. You will also receive automatic updates whenever a new version of Krita is released. For more information, see https://www.krita.org.