Along with visible modifications (vehicles specs, feature correction, regular bug fixes...), a lot of work is being done on graphic API, engine and so on. It's usually it's a few lines per update, up to a page of something looking like a foreign language for regular people. Some assets failing to load, loading too slowly, an internal action reporting an internal error, you name it. Dev stuff.
Listing those fixes would submerge what really interest players in a blob of... Klingon, and spending time to explain those would turn our updates notes into an online program development course.
Pic from https://live.warthunder.com/post/895213/en/ !
Skin from https://live.warthunder.com/user/JohnnyAlpha65/ (but i'm not exactly sure which one was used)