I have messed around with slick greeter before. Let me see if there’s something in the config file I can find
Edit I don’t see it anything in the two config files in /etc. It may just be a weird resolution on the wallpaper. I didn’t dig down to where it is but it is an endeavourOS wallpaper. I have never tried installing slick greeter on deepin. Maybe I’ll try. There is a guide here: