Icons don't scale at all whith GDK_DPI_SCALE or GDK_SCALE

Steps to reproduce

1. Set 4k resolution in manjaro-sway.
2. Set 'gsettings set org.gnome.desktop.interface text-scaling-factor 2.6'
3. Open 'pamac-manager', 'pcmanfm' or any other GTK application.

Current behavior

• Everything scales correctly except the icons, and the text inside some components.

Expected outcome

• All icons and elements should scale correctly.
• Alternatively, provide an env var to control icon size.

Version information

• manjaro-sway latest
• gtk3 1:3.24.30

Additional information