@Paradox its not that so much as the anime changes Tanyas character alot. take the scene where Ivonova is first assigned as Tanya's assistant. In the LN she's actually pleased to be working with someone she knows is reliable. In the anime she's bitchy about it for no reason.
Also in the very first episode (which is shown out of order) Tanya has two of her squad sent to man a pillbox because they refused to follow orders and put their fellow soldiers at risk. This is visually portrayed as her doing something malicious or evil when it was nothing of the sort. That pillbox was going to be manned by somebody sending those insubordinate who already have deathwish there was the most logical option to avoid those two idiots getting actually good mages killed alongside them.