It would be nice if the functionality that we see for time-sliders in Pro is available in Enterprise 11.0, or in-plan for a minor version.
Pro: Has the capability for the time slider to only show snapshots of dates actually included in the mosaic dataset.
Web Maps: However, when publishing the mosaic dataset as an image service in Enterprise 10.9.1, the web map settings currently do not offer this option.
Please add the viewing unique times functionally in ArcGIS Pro to ArcGIS Enterprise web maps and web apps.