Upgrade from 43.1 to 44.0 on Arch blocks initial render of GTK apps for minutes

Upgrading xdg-desktop-portal-gnome from 43.1 to 44.0 (or 44.1) makes GTK applications like Firefox and Gedit take minutes to do their initial render. After that they are both smooth, until a resize happens and it takes another few minutes to get responsive.

System

OS: Arch Linux 6.1.28-1-lts
WM: i3 4.22-4 (but also happens on sway 1.8.1-1 and gnome 44.1-1)
CPU: AMD Ryzen 5 5500U with integrated ATI GPU

Packages

gdm 44.1-1
gtk2 2.24.33-3
gtk3 1:3.24.37-1
gtk4 1:4.10.3-2
mesa 23.0.3-1
wlroots 0.16.2-1
xdg-desktop-portal 1.16.0-3
xdg-desktop-portal-gnome 43.1-1 (breaks on 44.0-1 and 44.1-1)
xdg-desktop-portal-gtk 1.14.1-1
xdg-desktop-portal-wlr 0.7.0-1
xf86-video-amdgpu 23.0.0-1
xf86-video-ati 1:22.0.0-1
xorg-xwayland 23.1.1-1

(too many installed system packages to list all, please ask for specific ones)

Environment

DESKTOP_SESSION=i3-with-shmlog
GDMSESSION=i3-with-shmlog

GTK3_MODULES=xapp-gtk3-module
GTK_IM_MODULE=ibus
GTK_MODULES=canberra-gtk-module

XDG_DATA_DIRS=/var/lib/flatpak/exports/share:/usr/local/share/:/usr/share/
XDG_RUNTIME_DIR=/run/user/1000
XDG_SEAT=seat0
XDG_SESSION_CLASS=user
XDG_SESSION_DESKTOP=i3-with-shmlog
XDG_SESSION_ID=1
XDG_SESSION_TYPE=x11
XDG_VTNR=2

XMODIFIERS=@im=ibus