The patch works to improve stabilization across the board on all platforms, fixing "global issues" according to the patch notes. On the PS5 specifically, a glitch has been fixed where a crash could occur when pulling in Photo Mode images on the world map.
It's a very minor update in the grand scheme of things, but nevertheless, you can view all the PS5 patch notes below:
Assassin's Creed Shadows PS5 Update 1.0.1 Patch Notes
Bug fixes & Improvements
- Stabilization - Fixed some global issues
- [PS5] Fixed a Photo mode issue that could cause a crash when fetching photos to display on the world map.
- [PC] Fixed a Photo mode issue that could cause a crash when taking a photo.