In the example shown, there are two rules applied.

The best option is to set up the rule correctly from the start.

you’ve got the option to access existing rules at Home > Conditional Formatting > Manage Rules.

Pivot table conditional formatting top 5 values rule

Then adjust tweaks in the “Apply rule to” section.

Note: conditional formatting is lost when you remove the target field from a pivot table.

Pivot table conditional formatting top 5 values rule

Pivot table conditional formatting top 5 values rule

Pivot table conditional formatting top 5 values rule

Pivot table conditional formatting top 5 values rule

Pivot table conditional formatting create new rule

Pivot table conditional formatting rule manager

Pivot table conditional formatting top 5 values rule

Pivot table conditional formatting create new rule

Pivot table conditional formatting rule manager