When creating a change to your environment using Design Extension.
Keep in mind - When Microsoft does an upgrade on your environment those extensions will be removed and you would not be able to install so you would have to re-create.
Best practice - to have a developer convert the designer extension to a true extension. Then, when Microsoft upgrades the extension would stay.
Using Designer
Designer in Dynamics 365 Business Central complements the development experience in Visual Studio Code. It provides an easy and convenient way to make immediate changes to your design by dragging and dropping the components on the page.
Extensions created using Designer are removed when the sandbox environment is updated or relocated within our service. Thus, you should not rely on using the sandbox environment as a source control for these Designer extensions but remember to frequently download and backup the Designer extension source.
Option 1: Preferred option is to create a Dev Request in CRM and make the changes via developers. The code will be stored in DevOps and Apps will be available in Production/Sandbox environments even after updates.
Option 2: If consultants are in customer site and need to make any changes immediately as per customer request then download the designer extension and create a Dev Request by attaching the designer extension or provide details of the extension so developers can go to environment and download.
Developers will then convert the designer extension to proper extension and store it in DevOps.
Number of hours spent by developers will be billable.
Option 2 needs to be communicated to customers as well if they are making any designer changes by themselves.