May 17, 2020
The two dashboards are connected with the same slice.
July 16, 2010
It's very difficult to help you without seeing at least screenshots, which you can anonymize before sharing.
You haven't said what the fields are in these PivotTables or what field the Slicer uses. I wonder if the Slicer is a Month field or week field, so when you apply the filter it has no choice but to filter all PivotTables it's connected to by that level of granularity.
You really need to provide visual information for us to help you further. Please use some image editing tools like Paint to remove sensitive data from the image before sharing.