Publish Changes from clean Project will overwrite Redwood customizations in lower Environment

Summary:

Our normal distribution of Redwood changes are from our TEST environment to PROD, which is working fine.

The changes deployed are also visible in our lower environment (like DEV) after a P2T.

I was asked by our users to setup a project, so that they can test early configuration changes in that DEV environment ad not spoil anything in TEST which is our single point for all production related changes.

When setting up a new project now only to be used for that testing in DEV, it happens that users still see the customizations which were done so far (coming from a P2T), but when they start updating a page in VB then these customizations are not visible anymore in the editor.