Thanks for the chapter!
Granted the MC collapsed do to overworking herself, but seems unlikely to have died hours later after stopping instead of then and there. Also, only 13 chapters in so can't be end yet. Best case she just collapsed and is recovering somewhere, hopefully not comatose, and are lying about her dying to either buy time before confronting the three rebellious dukes or she's going to help with situation as an agent with being dead to get enemies to lower their guard. Worst case she died and gets reincarnated again. Personally I think she's still alive as there wasn't a public funeral, rumors of her death spreading, and Anna at least would be tearing up and not smiling when presented by the King. Will have to wait and see what happens next chapter to find out one way or another.