There is a new pull request by orowith2os against master on the void-packages repository

https://github.com/orowith2os/void-packages flatpak-dep-update
https://github.com/void-linux/void-packages/pull/39844

Adds xdg-desktop-portal as a dependency for flatpak
Flatpak relies on xdg-desktop-portal heavily, why it isn't a dependency is unknown to me.

Additionally, it would make sense to add xdg-desktop-portal-gtk as a dep, since that's needed for GTK theming and a native filepicker in the event there isn't another xdg-desktop-portal implementation that has one.

A patch file from https://github.com/void-linux/void-packages/pull/39844.patch is attached