The fact that we need the entire xdg-desktop-portal stack for screen sharing on browsers is a major annoyance. We now have a standardised extension for screencasting and screencopy (formerly it was not standard, but had been around for years), but browsers only support the Flatpak stack, which has a lot of moving parts and IPC. Doing out-of-band IPC for this is kind of pointless when the client and the server already have a Wayland connection to begin with.

Outside of the domain of Firefox/Chromium, screencasting is much seamless. But 90% of the screen-sharing happens in browsers.