The artstyle of Amplitude games have changed significantly since Endless Space. I have jumped on the Endless train on EL, played some ES and really loved the sense of scale and epicness in those games. ES had some fine and true sci-fi vibes: somewhat alien, somewhat weird, somewhat harsh, but not convoluted and not too bright to become unbelievable. I had a real feeling of taking a part in a cool hard sci-fi story somewhat like in the Strugatsky and Yefremov books I used to read. Endless Legend was brighter and more fairy tale-ish, which is fitting, but it remained that part of "groundedness" and simplicity that kept the visuals relatable. So one of the main things that got me into Amplitude games was the visual design which had scale, epic, some alien/sci-fi feeling and at the same time was grounded, laconic, serious enough to be believable.

 So I really hoped that ES2 would give me those feelings again, that it would be ES but better, but it turned different in a bad way. The artstyle became too convoluted, too bright and shiny, as if it was some kind of teen cartoon or anime. I'm not saying it wasn't fun to play foor some time, but all the bells and whistles made it harder to look at and keep being invested - I was getting simply tired of all the shiny and flashy stuff on the screen. And the sense of scale and epicness went out for some cigs and never came back - I still look at Mezari battleships, art material, listen to ES soundtrack and think "yeah, this some epic sci-fi, almost space opera, i'd love to build things like this irl", but all the ES2 stuff seems like some kind of expensive and complex plastic toys. The new Empire, Vaulters, Horatio and other factions look like a parody or a tastless attempt at mimicking the old factions.

 But ES2 is still kind of grand and bizarre. Humankind loses even what is left of it. It is ok to lose the bizarre - after all, it's a game about our history, about humankind - but it is most appropriate to keep it epic, grand, serious etc. Humankind just looks bland and has no big feeling in its artstyle. It also looks like some kind of cartoon or some deviantart drawing which doesn't take itself serious, while it is most appropriate for a game about human history to look like an art gallery, historical drama or pages of a history book - which is exactly what does Civ V, for example, and what Civ VI does not (and this is why many people actually hate its artstyle). Civ V's style is referencing history in a serious manner, trying its best to show its greatness (which it fails n the end because of its civilization approach to explaining history), so in comparison Humankind looks just weak.

 And finally we now have Endless dungeon which is just a netflix cartoon crossed with *that* corpo artstyle and completely lacks any soul and any visual relation to the previous Endless games (even with DotE).
In the end my point is that to me it seems like Amplitude's skill of building a consistent and serious enough artstyle, which was a big part of Endless games' success, has completely degenerated, so I wonder if this is only my dumb head thinking like this, or other people have this feeling too, and if it do be like this, then what can be done to make Amplitude's artstyle interesting again.

All feedback is always appreciated. You can imagine I am a bit bias on the topic but I do not think/see that Endless Dungeon is "cartoon" at all (neither HK tbh). Perhaps it is because every time I heard about this in my mind I envision the Looney Tunes, and well, I don't see the similarity.
I agree that part of the style is different as the games are different, but still, I don't think the team has done a worse job at all. Perhaps the tone/vibe of the new games does not make a "click" for you.