Weird light source, without light source

engine version 4.27

For some reason my level has a weird light at all times, even when I disable all things except for a default cube (as pictured on the top photo).
What could be the cause of this?
I added the cube to a blank level and there’s no light.
If everything is invisible, how can I see the light?

Try this: change to Unlit mode. Then, change to Lit again.