Uninstalled a steam game but the space never came back

if it's still unclear where the space went, run WizTree or WinDirStat. it shows you which folders are actually big in a few seconds, saves you guessing which leftover it is.

Steam often leaves the folder behind, especially if there were mods, saves or config files in it. Go to your library folder, steamapps\common, and see if the game's folder is still sitting there. Delete it by hand. While you're in steamapps also check the downloading, shadercache and workshop folders, they can hold a few GB each for a game you no longer have. Settings > Storage in Steam shows what it thinks is on each drive, which helps spot the mismatch. If it was a big game with a separate launcher (EA app, Ubisoft etc) that launcher may have its own leftovers too.