Fields in Highlights Panel not updated when changed in the Case page layout

When Legacy Case Feed is active in an organization, the Highlights Panel on Case records draws its field configuration from the Case Feed Layout, not from the standard Case page layout. As a result, changes made to the standard layout are not reflected in the Highlights Panel.
Step 1 — Determine if Legacy Case Feed is Active
In Salesforce Classic:

1. Click Setup.
2. Click Customize.
3. Click Cases.
4. Click Page Layouts.

In Lightning Experience:

1. Click the gear icon and select Setup.
2. Click Object Manager.
3. Click Case.
4. Click Case Page Layouts.

In either view, check if a section called "Page Layouts for Case Feed Users" is present. If this section exists, Legacy Case Feed is active in your organization.
Step 2 — Resolve the Issue
You have two options:

• Option A — Edit the Case Feed Layout: Open the Case Feed Layout within the "Page Layouts for Case Feed Users" section and update the Highlights Panel fields there directly.
• Option B — Remove the Legacy Case Feed Layout: Delete the page layout listed under "Page Layouts for Case Feed Users." If it is the only layout in that section, this removes the section entirely and returns Highlights Panel control to the standard page layout.