Your problem is a bit like my problem described in this thread. A bug was fixed, destroying how my previous work rendered out.
I used object space normals in a way it was never intended due to the bug, now fixed so I have to rethink my strategy and do things the right way.
You setup lights in a way that was never intended, now fixed so you have to rethink your strategy and do things the right way.
If you are a developer, do you leave in a bug that is convenient to some who exploit it and make it optional, or do you fix it and say “sorry”? And what does industry standard look like to help answer that question? If you’re absolutely forced to keep the old look, you might be forced to stay with older Blender version as well.