Something bad is happening with Korean series, it happened to "Sweet Home" and it will surely happen to "Squid Game"...many years pass between seasons. The same thing happens to "Hellbound" which has an incredible, compelling, striking and dark first season and a second one, which although it is in that line, changes the focus quite a bit and we go from the mystery of the monsters and why they send people to hell to a more apocalyptic plot focused on humans. But all this, 3 years later, makes it lose interest and surely numbers.
I think that the series is correct, the script seems consistent to me and the performances as well. I especially highlight Min and the detective from the first season in the moments that he appears.
In season 2 the mystery is less than in the previous one but it takes it to a more political side. We are shown how the government intercedes between a religious organization and a group of religious fanatics in order to benefit and generate an order that no longer exists. On the other hand, we are shown the appearance of the "resurrected" but in two different ways: Park Jung-ja, who learned from her stay in hell and has a happy ending, unlike Jung Jin-su who did not and his actions lead to becoming another envoy.
The effects are better than in the first season, but as I say, it lacks the mystery that characterized the previous one.
Perhaps its biggest problem is the pace, at times slow, but not boring.
We will see if there is or not a third season, it would seem the most correct, but that does not mean that so much time passes...