That is super strange then, truly. If you click on the material, what does it say?
I did once have this absolutely bonkers error with lumen: VRAM would overflow and scene textures would corrupt into these super bright color patterns, and lumen would propagate that lighting into the scene, so my level would become an unwanted discotheque. Check if any of your textures have strange corruption artifacts, and check the surface cache if the areas emitting the strange highlights have proper surface cache coverage.