Made a slight error. Castlevania was animated by a Texas studio called Powerhouse Animation which outsourced to a South Korean studio. But holy crap they must have been animating it during breaks. Though my point is not that it was not animated by Koreans but rather that it did not conform to existing anime standards which these Korean animators are required to have.
Castlevania Season 1 doesn't look too bad. It is passable especially for a first season. They were notably struggling with Season 2. Honestly the series just ends with Season 2, don't know why they kept it going. Season 3 which sucked also has animation that looks like Corel Draw. With Season 4 they switched from Mua to Tiger Animation.
For the record Tiger Animation is their current animator from South Korea. Western animation frequently has relied on South Korean animation. Just as Japan has come to rely on South Korean animation in the past decade. Tiger Animation goes back to the 1990's with shows like Spawn.
They are also one of the many studios that is contracted to work on the DC animated films. As someone who has watched all the DC animated films I can really see the drop in quality both as animation and story writing. One of their most recent films "Justice League Dark: Apokolips War" was incidentally one of the worst in my opinion, only topped in poor animation and writing by "Wonder Woman: Bloodlines".
Now I can't really say much on the topic of Tiger Animation as a whole but with DC properties at least they didn't go with a faux anime art style. That is really the biggest issue for me. The fact that people confuse this with anime, which studios do intentionally. But is obviously not anime. Even though anime and Western animation tends to have a lot of Japanese work done on it, even anime, as poor of a state it is now has better standards than these western shows. Castlevania doesn't, and again I stress how unbelievably bad Season 3 looks.
But it is this attempt to copy anime styles across the globe (South Korea, China, USA, etc) and the obvious declining quality of Japanese anime, which has made anime redundant and is killing anime.