Redwood: Unexpected Behaviour of Read only property in fields of Revenue

Summary:

Hi Team,

When I go to Redwood Opportunity > Show products and then edit one of the products, a custom Revenue Edit Layout is rendered. This is a copy of standard layout.

1. When I try to access Read only property in fields like Quantity, Revenue and Amount, this property is not present.
2. There is an OOTB custom field present for these fields which has below expression. Please let me know what this means and how can I edit it to make it read only according to our needs
   {{ $functions.isAttributeRenderableForLoggedInUser('Quantity') ? {'Quantity':{'readonly': $variables.disableRecurrFields }} : null }}

Attaching screenshot for reference.