Going off the reflections off the metal bits above them alone they almost certainly have house lights on. So probably not a hot set. They probably were doing a quick blocking check/rehearsal with talent so they snapped a quick picture with the sticks. Only a guess though, Im mostly on the doc side these days.

If things are looking too dark, check if your TV supports some form of HDR. Shows like this will do a proper job with color and part of HDR is streaming a parallel file to the video to take over your TV settings and auto adjust l to optimize how they want you to see the final product.