Light showing up in render that's not in scene/viewport?

Hi - I’m a very novice Blender artist (I basically just finished the infamous donut tutorial) and I’m having some issues with lighting. There’s a light in my render that I can’t find the source of. I tried disabling the all the lights in the render, then deleting them one by one with no luck. I tried changing the World > Surface Strength to 0 but that didn’t fix it either. It’s not showing up in my viewport, and I don’t know what else to try.

I’ve attached a snapshot below. The background image itself is just a dark navy plane so the light spot is definitely a light and not something that’s part of the image.

Any help would be greatly appreciated!

Render image with mystery light (left) vs Viewport (Shading set to Rendered, right):

Can you give us the .blend?