1) The new CFF rasterizer automatically increases the weight of fonts at small
sizes, in order to maintain contrast and improve readability. To do this, it
assumes the system is adjusting gamma for text (as Werner mentioned earlier). In
most displays, I find a compromise of gamma 1.8 is best, but anything down to
1.4 should look ok. Your screen shot shows that that linearized blending is not
being used on the text. That is, gamma adjustment is not being done, and your
gamma is 1.0. Using gamma 1.0 has several negative effects on anti-aliasing; one
is to make black-on-white text look heavier. So, we are effectively darkening
the text twice. I don't know if this is a Fedora issue or a LibreOffice issue.
FreeType does have a control to disable darkening, and that might help work
around the issue if you can't get the system to do gamma adjustment.