Maxperson
Morkus from Orkus
It could have been some sort of subspace or spore dimension pulse. It may have even been caused by the Discovery as it moved through time. Perhaps time travel clashed with the spore element.So, over arching plot theorizing. All dilithium blows up at the same time. That has to be some form of sabotage. There's no way that's natural. But, it would make sense that the Federation would fall apart so badly. Every star system would be cut off almost instantly throughout the Federation and Klingon Empire. The Romulans might have avoided it, but, they are very far away, and, that far into the future, they might have integrated dilithium into their space ships anyway.