https://bugs.winehq.org/show_bug.cgi?id=40096
--- Comment #8 from Sergey Isakov isakov-sl@bk.ru --- I tested also Web Safe Color Palette but the screen looks psychedelic. No, it seems grey scale is the best solution.
There is also convert_p8_uint_b8g8r8a8_unorm() that can be patched the same way if it may resolve a bug with other game.