Full HD/4K video and uncanny valley effect, etc.?

Not sure which forum to post this in but this looks like a good one as any, since it makes me feel old already ;)

Just that our household (well, a certain member specifically) has managed to acquire a modestly priced 4K TV, and I decided to have a play about.

I noticed that watching videos I'd been used to watching on a crappy old laptop on Youtube, or suchlike, now looked almost hyper-real. The effect probably being only more pronounced with 4K. As in, it almost looks a little "too real", too crisp. I wonder if this is just used to seeing standard definition, nothing better than 1080i, or knowing me even old VHS tapes primarily.

Has anyone else noticed this? I feel I am probably late to the party, as much as I always like to gawk at the latest high-def TV stuff in the shops to see how good it is, we tend to be relatively late adopters and for financial/stick in the mud reasons me more so than most.

(There is a counter-effect, though: that possibly due to the TV's limited processing power with 4K or perhaps upscaling effects, the picture sometimes seems to jerk or move at the wrong speed temporarily.)

Apparently explained here...

https://www.howtogeek.com/182926/ask-htg-why-does-my-new-hdtvs-picture-look-awful/

I've definitely had that effect from HD T Vs and from seeing the first Hobbit movie in 48 FPS in the theater.

I equate it to getting new glasses after putting it off or too long. You spend a week or two weirded out by the extra crispness, but then get used to it as your brain adjusts.