If you add a "screen capture" source, then edit its properties, then click "open selector," are there 2 tabs at the top of the selector that say "screens" and "windows"? If you click on the "windows" tab, it should behave like a "window capture" source.
It sounds like any desktop environment that's using Wayland is now using this window selection method VIA the "screen capture" source, rather than having the standalone "window capture" source. I run Garuda & had the same issue; it took me a little time to figure out what was going on there! Let me know if that helps at all.