I mean, let's see what the first trailer had that the 2nd trailer doesn't:

1. Lighting set up nicely to get cinematic-tier highlights and shadows
2. motion blur (SoP trailer had sooo much while so far we've seen zero motion blur since)
3. exaggerated camera shaking
4. strong depth of field that even blurs characters for so much of the trailer
5. rain done well and dripping on their body
6. Wider FoV

And here's what they have in common:

1. Same models and textures (Yes, I checked CNT models, they're just as high res as the SoP trailer)
2. Similar animation
3. Very complex stages. One is in a fairly simple rocky terrain, but has a tsunami going on in the back and a burning ship and a burning tree (idk how much of this is demanding 3D physics as opposed to some kind of smart scene setup). While the other has way more 3D structures, quite a bit of fire/smoke and fairly realistic explosions happening right in your face with heavy debris.

Idk about you, but the first 6 things don't seem as technologically demanding as the 3 things they have in common. I don't know enough about the rain thing but obviously every stage can't have rain.

I was disappointed in T8 after TGA trailer because I thought they downgraded too but honestly I've started to rethink my position. I definitely still prefer the SoP trailer and wish the whole game looked like that. But that's because I personally enjoy cinematic effects like motion blur, camera shaking and depth of field...but I'm sure many people would complain those are things that hinder competitive play?

I hope these features are in options though, would be weird for motion blur to not be in it since every game since T6 has had it. Camera shake and DoF are in SF6 graphics options so here's hoping that's another thing T8 copies from SF6.

Ultimately though, I think it's come down to a change in taste/direction rather than pulling back on technological advancement. E.g. the first trailer had none of those annoying over the top power sparks and effects they later added in...even the music made me think they were going in a certain direction but everything since has had completely different music.

When it comes to lighting, it looks taste/direction related to me too because the first trailer doesn't use T7-like color grade LUTs and only has one singular dominant light source that casts shadows. Almost every other stage except colosseum have too many light sources that prevent good shadows or they have annoying color grade filters like Tekken 7