I concur, it probably rather indicates "maintenance hatch" than "ejection" (though it doesn't exclude this possibility). You can have a yellow alert in spacedock, but I'd find a yellow "eject" while in spacedock rather unlikely.
Other yellow rectangles (saucer surface, starboard saucer underside) are probably personnel hatches. The yellow rectangle behind the bridge is a bit enigmatic. Either it's an access point for a docking tube in spacedock or something else.