MSFS 2020 Items Slowly Becoming Available in MSFS 2024 Library

I absolutely can prove that is not the case. Ref bug report and screenshots in Cannot unselect “streamed” packages in my library

There are no other 3rd party sceneries installed so that is the only conflict. And the marketplace sceneries breaking new FS2024 sceneries is pretty commonly reported in other threads so no - a lot of marketplace addons have not been tested for compatibility and released.