How to change zoom in login screen (SDDM)?

Question

linux

I have Linux Mint installed (18.3 Sylvia, KDE Plasma 5 (Sort of)). The problem is that at some fine moment the login screen (user login and password) became fucking big. The monitor is a large screen TV. It's like someone turned the percentage scale up by 500. How can I get the scale back?
(I myself didn’t change anything on the login screen except the background image. And yes, they didn’t get banned in Google. But all I found was questions about a black screen after login, and general questions like: “How to change the theme in SDDM”).