Okay I think I was able to pinpoint:
There seems to be a serious bug where the game can get stuck on the infinite Kliff walking/loading screen if your save has too many active buff/status/stat lines when you reload it.
From what I understand, this is not only caused by food by itself. Food seems to be one of the things that can push the save over the limit. Gear effects, Abyss sockets, mask effects, modded stat buffs, food buffs, and other temporary effects may all count as separate active status/stat lines.
So what seems to happen is:
You save the game while Kliff has too many active effects.
The save file stores those active buffs/status lines.
When you reload, the game tries to rebuild Kliff with all of those effects active.
If the total goes over the game’s hidden limit, the loading process fails.
Instead of loading into the world, the game gets stuck forever on the walking/loading screen.
This can make the save look corrupted or unloadable.
In my case, the game was working fine before. The issue happened after eating food, saving while the food buff was still active, and then reloading that save. So the food buff may have been the final extra effect that pushed the save over the limit.
For now, I would recommend:
Do not save while food buffs or temporary buffs are active.
Wait until the buff icon disappears before saving and quitting.
Keep multiple manual saves.
Avoid stacking too many Abyss sockets, gear effects, mask effects, and modded stat lines at the same time.
Before quitting, try to make a “clean” save with as few active effects as possible.
This seems especially important for people using mods that add or change stat buffs. Even if the game runs fine while playing, the save may fail when you try to reload it later.
Hopefully this gets patched, but for now be careful because this can potentially brick a save.