I've cleaned all caches (pacman, firefox...etc), still takes up 83GB.
Summary:
My swap is 16GB is the biggest file on this partition.(I needed that)
Flatpak repo is ridiculously fat, I've not installed too much apps from it. But OBS alone is gonna take 1~2GB due to sandboxed video codec and nvidia driver.
Waydroid takes some spaces but not too crazy
I also have installed full CUDA toolkit for AI purposes. (That's another 6GB, ouch)
Lutris: it created a new container for each game if you don't manually configure it. Each wineprefix takes up to 700MB~2GB. (I've already deleted couple of them in the screenshot)
all snapshots were deleted due to no space to update