Mega Drive model 2 PAL VA0 board Everdrive Evergenesis V3
Just try playing through level 5-2, moving slowly and eliminating all the foot soldiers. Once none are left, move forward until you encounter more. If you see a candelabra with a candle, break it. Continue moving slowly until you reach the boss of level 5-2.
You’ll see that there are no graphical glitches.
My suspicion is that the Mega Drive’s VDP glitches out when it has to render too many sprites at once. Each foot soldier you eliminate means one less sprite on the screen.