Weird Render Issue

I have a problem that seems to have appeared out of nowhere.
For some reason, a scene is rendering very differently than it should;


The top image is the Viewport Shading preview and how it should look (and has rendered just fine in the past), the bottom is the render as is happening currently.
It’s a somewhat older file, being 6 months or so since I last worked on it - but this is the first I’ve ever seen anything like this, so the only thing I can think of is that it is due to a Blender/Driver update. (Have also double and triple checked that everything is in order in the Outliner view, nothing enabled in Render that is not also enabled in Viewport)

I just installed Blender 2.93 and updated to the latest Nvidia Studio Driver, doing CUDA render in Cycles with an RTX 2070 Super.

does it still look weird in the older versions? Can you share the file? That looks like a huge light source is hidden in the viewport view.