Why? They all have a common publisher - Warner. On the macOS side, they lost even more as a few Lego titles also vanished and Batman: Arkham City too from mentioning macOS. The change happened just before the end of 2020 on both titles, as seen on SteamDB ( #1 - #2). It seems Feral Interactive have a few less ports available to buy supported for Linux and macOS to start off 2021 with as both Mad Max and Shadow of Mordor have been delisted for both platforms.