Recently checked games save folder and found there was a lot of files, every don't starve day that I played had it's own save file. (screenshot below)
Even after deleting save slot in the game, these files remained. And because of steam cloud sync, you can't delete them manually because they will be downloaded again (I know there is a way to delete files on steam cloud).
First file from this chain is named "shipwrecked_3_day014" and it was created on 16 September. I think update which came out that day might have broken something.
Steps to Reproduce
Play the game and then check save folder.
This issue has been fixed in either a future version or updated in a previous version.