Ah, well it's not a critical issue, but it's best to avoid, since it could potentially affect performance. I think this basically happens when you've got lots of overlapping lights. I'm not sure of the exact rule, since I think you can get away with some overlap, but to avoid it, I try to minimize the number of lights I use, and try not to let the cones overlap.
You can get away with fewer lights than you might think, due to the light bouncing off of the white walls. Try reducing the number of lights, and build lighting and you'll probably find it's bright enough. It works best if you set the lighting quality to production (just let me know if you can't find where to do that).

Ok thanks i will update the light system on Labor and Inspiration_02

Sure! I think I'll try and do a video on lighting soon, since I've been getting a lot of questions on lighting from others too, and it's reminded me what a complex topic it is, haha

Yep as i started to build Labor i did not noticed the build button so o tryed 30 minutes to make the map bright and ended with 50 Spot Lights. :)

Oh, haha! Yeah, you can probably get away with like 5-10

Yep :)