To enable screen capture in OBS under Wayland, install wlrobs.
Follow the instructions found here.
(Install mercurial first, if required.)
# clone and compile
hg clone https://hg.sr.ht/~scoopta/wlrobs
cd wlrobs
meson setup build
ninja -C build
# copy plugin in place
mkdir -p ~/.config/obs-studio/plugins/wlrobs/bin/64bit
cp build/libwlrobs.so ~/.config/obs-studio/plugins/wlrobs/bin/64bitRestart OBS and add a "Wayland output(scpy)" source to present your screen.