How to set differents "Custom all value" for a dashboard with multiple datasources

I have a dashboard gathering metrics from 2 different datasources (Mimir and Vertica).
For Vertica, the “Custom all value” of my variable needs to be set to ‘%’ to filter all values.
But I also have a panel using the same variable but which is querying from a Mimir datasource.
I would then need to have a distinct “Custom all value” according to the datasource.
Is there any possibility to achieve this?
Thank you for your insights!