OK I'm with kcpr-raffaEl
..the previous functionality of render region is a must for me as well, it became part of my workflow, where I can re render the whole thing, making everything black around it also give different sense of contrast this will add to potential confusion in workflow for sure
I also would like it back. It saved my a lot of time. For example when I rendered different color variants of a product render on the fly or tweak materials with open viewport.
Hi mbetke, kcpr-raffaEl
You can have the render region back, as previously, by unchecking the option 'User Region as Film Region' in the Viewport tab of Global preferences.
A more convenient icon in the viewport will be added in the future, to have a similar interface as in Stand Alone..
Thanks for the feedback on your workflow.