https://screenrant.com/star-trek-khan-ceti-alpha-vi-explosion-answer/

Star Trek: Khan gives the true reason why Ceti Alpha VI exploded, which doomed Khan and his people's attempts to build a paradise on Ceti Alpha .

Star Trek: Khan Ending Explained (https://screenrant.com/star-trek-khan-ending-explained/)

Star Trek: Khan concludes the true story of what happened during Khan's exile on Ceti Alpha V, which fundamentally changes what we know about him.