Nowadays the warning even says that this cannot be undone. Maybe that wasn’t present in 1.15, though.
It was. If you go through the OP thread, one of the responses is a picture of the dialog window that this user clicked through saying, “these changes will be IRREVERSIBLE”.
The OP was just playing with a new kind of fire (VSCodes Git/source control panel) that they didn’t understand, and they got burned.
We all gotta get burnt at least once, but it normally turns us into better devs in the end. I would bet money that this person uses source control now, as long as they are still coding.