Does CSS validation affect SEO, which site should view it?

Question

css

https://jigsaw.w3.org/css-validator/
www.cssportal.com/css-validator
www.css-validator.org
- these services give errors that are no longer errors.
Do css errors affect SEO and what errors?
Why I ask:
One of our sites went up dramatically in SEO even though we didn't do anything with it. There were several errors in the html layout and a couple of errors in the CSS validator.
On another site, due to the included css libraries (animation.css), there were 500 errors (I never checked this before), and html 0 errors. And he went down in SEO.

Answer 1

Surely it does, but probably not so much that there would be a noticeable decline.
There are many factors, you are clearly missing a more significant one.

Answer 2

No, it does not, changes could occur due to weight, page load speed

Answer 3

Use this gtmetrix service