I had the same problem after spending roughly the same amount of hours as you (54 hours). So I did some digging myself and testing. I can load some saves but every new saves (or auto saves) I make after will be corrupted automatically. When comparing the size of the save file between a new playthrough and the old playthrough, there's a drastic difference between the size of it. For example, a brand new playthrough will take up about 1.24mb, and my old 54 hours playthrough takes up 8.16mb. My speculation is that the save file increases over time, and at one point, the game will not be able to load it due to the size. Not sure if anyone else experiencing the same problem, but when you compare the loading of a old save and a new save, the time it takes to load a old save is much longer than a new save. I had to wait up to 2 minutes with a black screen for the game loading screen appears. That's all.55 hours in and all of my saves and auto saves load me back to the title screen with the message "saved data is damaged and cannot be loaded".
Is there any recovery potential or did Every save and auto save I have get corrupted at the same time somehow?
So how do you get that file size down? By dropping items? Scrapping items?