Is the approval status column in your SharePoint list a choice field? If so, you need to use the dynamic value that includes “value” in its name. For example, in one of my flows, I use: equals(triggerOutputs()?['body/WorkflowStatus/Value'])
To see the difference, add the Approval Status and Approval Status Value from the dynamic content into a Compose action. You’ll notice they return different data. Alternatively, you can update your trigger condition to use the value returned from the current dynamic value in your expression.