Semi-transparent creatures combined with no natural light makes things look unnatural at that depth. Also, considering many things are bioluminescent at that depth, that creature in particular might be generating its own light.

Edit: wow I'm dumb and misread. I thought you were talking about the first image. Yeah, the second one is very fake

2nd image is from the movie "Lighthouse", and that's just how it looked.

It might be from that outreach program to kids - I even saw something made up to look like a mermaid in there:-). Anyway yeah, whether made for or by kids, it's definitely stylized.

Yeah, tineye doesn't find any matches for it but does for all the others.

The backlight could be sunlight, but the it wouldn't be deep-sea. It could be another submersible with a light, but I don't know why two would dive together. The bokeh looks pretty weird also. I think it's AI.