How would I specifically get the timestamp of when an upstream asset was last materialized? Should I add it to the metadata in the asset's output? Or is there a way to access the timestamp that's given by default on Dagit for every run

in a downstream asset, you can access that info through the Dagster Instance. here’s a answer to a similar question, where info is passed down via metadata, but as for timestamp, it should come with the asset materialization event. https://github.com/dagster-io/dagster/issues/8521#issuecomment-1334617489