I am trying to make a lookup relationship field read-only in the UI. I marked it as read-only in the Page Layout and Lightning Record Page, but the field is still editable.

I am trying to change a lookup relationship field from editable to read-only, but the change is not reflecting in the UI.

I updated the field to Read Only in both the Page Layout and the Lightning Record Page, but it is still editable in the UI. I am not sure why this change is not taking effect.

My requirement is:

• The field should be read-only only in the UI
• Users should not be able to edit the field from the record page
• The field must still be updatable via code (Apex, Flow, API, etc.)

What is the correct way to make a lookup relationship field read-only in the UI without restricting updates made through code?