6316212495
Are you able to set a default wallpaper (MIUI-original)? Have you installed a different font? Sometimes they appear to be incompatible  with a theme, or the theme itself becomes incompatible with a new(er) MIUI-version.

Hi.
I didn't install any special font.
I just tried to install a few new themes, including Miui theme, still not able to see the default wallpaper.

Screenshot_2021-08-30-10-30-03-692_com.mi.android.globallauncher.jpg
Screenshot_2021-08-30-10-33-10-711_com.mi.android.globallauncher.jpg
Screenshot_2021-08-30-10-31-55-166_com.mi.android.globallauncher.jpg