I think your user name comes into play here...
Chernobyl is now the best rated TV series of all time. That’s one thing, what is more surprising is that this is despite being extremely challenging material that is often very difficult to watch. This wasn’t an easy sell, nor a crowd-pleasing proposition. Collectively, the production achieved something really remarkable.
Several have mentioned the feeling of dread that permeates the show, and I’d have to agree with that. Of course that’s a cumulative thing - wring, acting, directing, cimeatogrsphy, production design and more. But central is the score, which is genuinely remarkable. To condense this down to the most misplaced of Spinal Tap references and a discussion of why sound design scores are boring and obvious... well by all means take all the rope you want.
The score will only make sense in context of the film, which is any score’s primary function of course. And those results are pretty extraordinary. Huge respect to Hildur.