It's the end of open-contributions for one specific repository, that is all. It only covers QGIS, the UI application, not GDAL/GEOS and the other libraries that give it its functionality. Additionally, in the past few years the number and popularity of new open-source projects that do accept open contributions far exceeds the few old ones that do not.
You're forgetting QGIS's own plugin ecosystem, which afaik doesn't prohibit slo-... err, vibe and assisted-coded contributions.
Although that would probably change of the AI-assisted spam shifted over to it.