With endwalker showing that time travel uses the closed loop design, what is up with the 8th umbral calamity timeline?

The crystal tower and graha tia still exist, and also in the first while at the same time in the source. Without the 8th umbral calamity Graha would never come to the first.

The closed loop design implies that the 8th calamity wasnt really stopped but there's no Garlemald anymore to deploy black rose, so even if another shard ends up going full light the source has been changed to a very big degree for closed loop to be a thing.