Qt Flatpak apps running on LXQt can not properly follow the user-configured font size and DPI due to the lack of an XDG desktop portal implementation for LXQt. Eventually this brand new implementation should be available for Debian:
https://github.com/lxqt/xdg-desktop-portal-lxqt
Meanwhile, this workaround has been pre-configured in the SpiralLinux LXQt edition to make it use the correct Ubuntu font with slightly more comfortable DPI:
Qt Flatpak apps running on LXQt can not properly follow the user-configured font size and DPI due to the lack of an XDG desktop portal implementation for LXQt. Eventually this brand new implementation should be available for Debian: https://github.com/lxqt/xdg-desktop-portal-lxqt
Meanwhile, this workaround has been pre-configured in the SpiralLinux LXQt edition to make it use the correct Ubuntu font with slightly more comfortable DPI: