Emulator

Broken in 5.0-1473 -> https://dolphin-emu.org/download/dev/c505ce83984a2d20b99b8940c07dab9b50868765/

Looking at the fifolog, the game does shadows by drawing an object with only alpha writing enabled (colors aren't written), and then it performs an EFB copy of the alpha channel and uses that for drawing the shadows. In object 84, the TEV "b" entry for alpha is a constant alpha value of 255, and the "c" entry is the rasterized color which comes out to an alpha value of 4. With the TEV alpha lerp change to fix #5197 (which disabled/invertex the special rounding logic for lerping for alpha), those were multiplied as 4*(255/256), which rounded down to 3; now, they are multiplied out as 4*(256/256), which comes out as 4. (The EFB can only store 6 bits of alpha, so 4 is the lowest nonzero value it can store.) The important point here is that this game directly cares about the way the multiplication works.