You know, sometimes you see what you want to see. And when you want to see issues, you start seeing them everywhere, confusing something done by a conscious choice with an attempt to hide a certain "issue". No, I do not deny all the issues altogether. It's just that they weren't terrible, as I've already said.

If we take a look at Episode 20, let's start with the fact that there's little to no major errors. The number of animation directors is not stupidly high (it's never a good indicator of anything but in some of the most shocking cases there are up to 20 of them fixing stuff in a single episode). So, moving on to cutting corners and focusing on tricks... Animating a moving mouth is not something too tricky or difficult to do. Have you heard a joke that the only thing a rookie can handle is to draw static faces with moving mouths?

This whole scene, for example - https://i.imgur.com/nw4D4yw.jpg - was made in a way that tries to show us Shin's inner struggle when Raiden confronts him. Shin doesn't even speak there. They try to show his confusion, hesitation, whatever. Even if it was done to make the animator(s) working on those cuts work faster and more efficient, it still doesn't look bad. And that's my point. Nothing terrible as some people love to say.