Font rendering in WebKit (in 20.04)

I'm using cutycapt for webpage screenshots creation since Kubuntu 16.04. When I switched to Kubuntu 20.04 I noticed some changes in text rendering. In 16.04 text was rendered with full hinting, as was set in my settings (both in System Settings > Fonts and in /etc/fonts/conf.d/). In 20.04 despite the same settings text is rendered with only slight hinting which produces less clear, blurry fonts.
As far as I know, cutycapt uses Qt WebKit backend when capturing screenshots. Maybe something has changed in the newer version of this library and now slight hinting setting is hardcoded in it? Or maybe it is a bug that prevents honoring of system hinting settings?
If not, how can I achieve full text hinting on my screenshots?

I provided several examples for comparison in my AskUbuntu question here: https://askubuntu.com/q/1372953