Discussed before in your other thread. I tend to agree with @cgrunenberg this sort of folder renaming is seen in cloud sync services, especially when set to be “online” when there a conflict and they do it so as to not accidentally delete data.
Consider this renaming a blessing, not a risk, IMHO. And check you haven’t now or in the past did your cloud sync with “online” on. And remember when you expose your computer to sync services, you’ve given them some sort of liberty to manipulate your files and folders to do the sync you expect.