Exchanging money for a feature is not a donation. Skymatic UG is not a charity/regional equivalent to a 501(c)(3)(USA). It is purchasing a feature; a basic act of commerce.
This is the first supposedly F/OSS software I have encountered to engage in such sematic games. More unsettling is this is over a trivial function that only enhances the end user’s appreciation of the application if a custom theming engine is not supported.
I question the professionalism of the CTO. Please forward this post & query to him: when was the full suite of various applications last audited?
I look forward to a link/pdf.