I'm using Odoo 18 Community Edition and need help with a specific requirement for invoices created from sale orders.

Current behavior:

When an invoice is created from a sale order, users can still modify all fields including the customer, price, and quantity.

Desired behavior:

I want to lock only specific fields (customer, price, quantity) so they cannot be modified after the invoice is created from a sale order, while still allowing edits to other fields like tax and date.

My question:

What's the most straightforward way to implement these field-level restrictions in Odoo 18 CE? Is there a configuration setting I'm missing, or will this require custom development?

If custom code is needed, I'd appreciate a simple example showing how to implement this restriction properly. I'm looking for the most maintainable approach with minimal code.

Thanks in advance for your help!