Sometimes, while editing an instance of a symbol, all content within the symbol disappears or gets upscaled to some incredibly big size exceeding the borders of an artboard. The operation isn't listed in history so you can't undo. The bug is encountered in a seemingly random manner when working on files with multiple symbol instances. It is an old bug that I encountered in previous versions too.
Macbook Pro 2015 Retina, macOS 12.6 Monterey.