My Windows "fun" was when it decided that the "unknown" space immediately after its little boot partition was free for it to expand into. (Imagine not being able to recognize an ext2 filesystem...) After repairing that disaster, I ensured it would never happen again by putting Windows onto its own harddrive. That's worked for a great many years.

Though, now that I've quite a bit of personal experience with how good Steam/Proton is for video games, I think I'll reclaim the surprisingly large amount of space that Windows is taking up.