That Screenaver, (aka moving wallpaper on a smartphone - I had to check) is like the Screensaver available on my other older phone, a Moto E6 Plus on Android 9.
You are correct there's no Screenaver option on Xiaomi phones, I have their Poco F2 Pro, but their Wallpaper Carousel setting and the many available screens is similar afaik.
As you had a Lenovo and they own Motorola you must have that image downloaded somewhere on your new Redmi.
Probably under Wallpaper Carousel or it's using that image for that purpose.
I don't have Hyper OS but the previous MIUI 14.
I'm sure there is some way you can turn that off.
Do the colours move slightly at all? Mine do if I select that as a Screenaver. I never bothered with things like that I just set Screenaver to a digital Clock on a blue wallpaper background.
See here on my Moto: