https://bugs.winehq.org/show_bug.cgi?id=41930
--- Comment #47 from Bryan Varner bryan@varnernet.com --- Upstream bugs related to Civ3 and OSMesa / Gallium Frontend
OSMesa Gallium frontend disregards (obliterates) user supplied buffer contents. https://gitlab.freedesktop.org/mesa/mesa/-/issues/5094
This second one may need to split to a different bug in WINE, as this can't possibly be only manifest in Civ3. Surely there was another app using 16bit off-screen WGL?
OSMesa Gallium frontend using 16-bit packed pixel format with inappropriate color channel spec for WGL https://gitlab.freedesktop.org/mesa/mesa/-/issues/5095