CGI
CGI is always kind of tough to rely on. When it works well, like on Game of Thrones, it looks fantastic but drains the budget for the show.
When it doesn’t work well, or doesn’t have proper funding, it looks unnatural and can ruin the ambiance.
For the most part, The Witcher doesn’t rely too heavily on using CGI for that reason. Instead, it focuses more on practical effects.
According to the producer Lauren Schmidt, this was deliberate, as they avoid using CGI to make things more authentic. This was made pretty clear during one portion of The Witcher when CGI was actually used.
The scene, in particular, I’m referring to is the Golden Dragon, Villentretenmerth, in episode six. The CGI was bad enough that it looked more like the 2001 Polish adaptation of the books, The Hexer.