The last two posts were caused by Xcode: it wanted to update, but all of a sudden I have JUST 8 Gb of free space, which is not enough. Spoiler: 14 Gb is not enough either, I think it started updating when I freed at least 20 Gb or so.
So... why does Xcode, which itself weights 12 Gb and IS ALREADY INSTALLED, need as much of an additional space to update? Just delete what you have and use that space for the new version. Right? Right? You can’t use it while updating anyway.