> I think this an actual PCB also
or an old version of MAME, there's another on there that looks more like a PCB because it has some odd bordering effects.
that's why I'm wondering if it was meant to be a simple wire mod on the PCB or something tho, something that could have fallen off on more than one PCB, or that people have removed when 'cleaning' the PCBs without realising why it was there.
I can't explan why they would set extra bits in the sprite attributes on those sprites for any other reason than putting them under the tilemap, and in every case where they get set that I can see it looks like the sprites should go under the tilemap. There's literally no other effect that bit could have.
So either every copy of the game is broken and doesn't work as intended on hardware, or there was some mod to the hardware that has been lost... It's a very difficult one to call.
Again given the original priority fix came from a Japanese developer I'd be hesitant to call it wrong.