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Read the C++ Qt docs on the context property usage. I think it may explain why there are better approaches. Dropping in things into the global QML engine context has the same negatives that using a global python variable has - global namespace pollution. No easy way to organize your properties you're sharing to QML.
However, it's a really easy way to share data from Python or C++ (host language I guess?) to QML. Though I believe things got easier with Qt 6 and PySide6 in this regard.