Game Progression Lost on PS5

I finished the game today and was doing some side stuff afterwards, mainly bounties. I finishes a bounty and fast travelled to the mantis which caused my game to crash. This is probably the 2nd time the game as crashed for me, so i simply reloaded the game to continue where i left off.

When reloading the game i get a message in the top right saying 'fixed your game due to data corruption' which i thought was weird, and then when i'm in the game, my save is now on the mission 'climb mountain to the obssrvatory'. My PS5 has automatically deleted my finished save game, and replaced it with one that took place HOURS before the point i was at before the crash!

And i don't have ps plus to upload the saves to the cloud, and i didn't have a usb stick either cause i didn't think i would need to! And i only had one save file cause thats just a thing i do, i don't feel the need to create multiple saves when playing a game. I am so angry and upset rught now, does anyone know if there is a fix for this or am i just completely screwed cause this is just so WRONG!