I don't have a Hi-DPI screen so I'm unsure about all the details.
My understanding is that you need to configure HiDPI for Qt apps separately.
I think that GNOME Shell 3.25.90 doesn't really support HiDPI for X, just for Wayland. That may be a regression, but Hi-DPI support in GNOME Shell has been redesigned to prepare to support fractional scaling in Wayland in a future release and it may be a lot more complicated for all that to work well on X too.
I don't have a Hi-DPI screen so I'm unsure about all the details.
My understanding is that you need to configure HiDPI for Qt apps separately.
I think that GNOME Shell 3.25.90 doesn't really support HiDPI for X, just for Wayland. That may be a regression, but Hi-DPI support in GNOME Shell has been redesigned to prepare to support fractional scaling in Wayland in a future release and it may be a lot more complicated for all that to work well on X too.