Oh! So, here's that render, 20 hours 45 minutes in:

Now, I'm re-doing the render, but with an IBL and taking out the skydome. After only 20 minutes, the clarity and detail is remarkably different! Seriously, the graininess is already less than the 20 hr render... I really think that it might have been the skydome. Well, lemme show ya... 20 minutes, mind you:

Interesting.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks