@be I'm really not getting what's the problem. This is just a tool that's appeared in response to the demand. Nobody requires a developer to use it. There are Open and Free projects and commercial projects. A lot of commercial projects use QT. Moreover, QT isn't completely free. Such projects require this an option and are using different solutions already. QT is just responding to the market. This isn't about Open Source in any way.

@be For instance, I really like Flutter. I believe it's going to destroy QT on the market. Dart and Flutter are Open Source projects and the community is awesome.
Nevertheless, they develop similar libraries for adding ads to cross-platform applications developed using Flutter. This doesn't prevent the development of a lot of new Open Source apps using Flutter in any way.