It's because they barely have any screentime. And their storyline barely moves and is rushed in the end. There are too many subplots and side characters for like 60% of the show, so Khatha and Dome barely get any screentime. Hell, the side characters get so much screentime that they can be called the main characters at this point.

If I make a Gun Atthaphan cut for this entire show where he is awake and acting instead of being unconscious or stuck somewhere, it would only be of 30 minutes max. And the plot in itself is a mess - is it about time travel? Multiverse? Mythical creatures? Inspired by religious things? Black Magic? Cults? You wouldn't know because it is a clusterfuck of all of these.
(Since when centuries' old magically summoned devils started dying of mere bullets? lol)

But still 2 episodes were very good storywise- the one with memory butterflies (the acting was top notch) and the episode where The One appears for the first time (Gun can play multiple characters well).

Such a wasted potential that it left me angry. It could've been so much better. They have left an open end at the final episode hinting at a season 2 but I wouldn't wanna watch it if this is what the director is gonna do again. The VFX was trash too towards the end. Tor Thanapob as Khatha was amazing but even he couldn't save this show for me. But I will look forward to his work from now on.