Link to the above mentioned post here:
https://forum.makecode.com/t/share-links-and-editor-magic-url-confusion/16173
Maybe one of the reasons for the links to expire is if someone presses “Report abuse”, where the shared game is just deleted and no notification given to the sharer?
(Hope I am not an abuser)
Are there other reasons why a shared MCA game link might expire suddenly/over time?