Multi-value variable formatting limits in chained Grafana dashboards

Grafana dashboard variables support multi-value selection, allowing panels to receive arrays or formatted strings for dynamic filtering. When variables are chained, a parent variable's selection filters the options available to a child variable, creating hierarchical dependencies. The documentation notes that multi-value variables can be passed as arrays or formatted strings, but the exact interpolation syntax varies depending on the data source plugin. Additionally, the "All" option can be configured to send a specific value or a regex pattern to the underlying query.

High-cardinality variables are associated with significant browser-side memory consumption and slow dashboard loading, while complex chained variables may cause cascading query execution that increases load on the data source. These behaviors raise questions about the practical limits of combining multi-value selections with chained dependencies, particularly when the "All" option is used across plugins with different interpolation requirements.

What documented limits exist for the number of values or cardinality of multi-value variables in chained configurations? How does Grafana determine the final formatted string sent to the data source when a chained multi-value variable uses the "All" option with a regex pattern? Are there plugin-specific constraints that prevent certain multi-value formatting patterns from working reliably in cascading query scenarios?