GNOME automatically set scaling factor to 2 when HiDPI is detected.
Unfortunately it does it also on not really HiDPI displays, making the
whole UI unusably large. There is no middle ground - scaling factor must
be integer, so 1.5 is not supported. Lets opt on a conservative side and
fallback to scaling factor 1.
Solution by @alyssais, thanks!
FixesQubesOS/qubes-issues#3108