Yes, the game promises you that the rot will increase with every death, eventually killing Senua permanently. It just, well, doesn't. The rot will grow to a certain point - which we think is governed by how far through the game you are - and then stop. In fact, this happens fairly quickly after a couple of deaths. Details, and fifty of our own deaths, in the video above.
https://www.pcgamesn.com/hellblade-senuas-sacrifice/hellblade-permadeath-bluff
More at the link..
Direct youtube link to the video
https://www.youtube.com/watch?v=JM3sxy21j3k
So it looks like the Permadeath stuff is being blown out of proportion..