I just played a session and noticed that saving didn't work properly anymore - I would enter a save name and hit save, but afterwards, the save would not appear in the list. When I tried to reload the last appearing save in the list, the game told me it detected save corruption and could not load it.
After the initial wailing and gnashing of teeth, I noticed that the last save in the list, the corrupted one was right after some milestone. I reloaded the last working save, played up to the part where that corrupted save would have been and noticed that it was right after some cutscene where the game would have been autosaving WHILE I initiated the quicksave. It seems that you can royally screw yourself if you cause overlapping save procedures, so for the foreseeable future, I will make sure that the only one initiating saves is me, no more autosaves here.
tl;dr: If you save while an autosave is being made, your save will risk being corrupted. Generally don't overlap saves in progress.
My software Spidey-sense says that whichever saved second is OK.
I'd say that either the opposite is true or both are borked due to the following considerations:
I assume the autosave begins immediately after the cutscene, before I run through the hoops of seeing that the cutscene is over and then either going into the save menu to type a save name or hitting the f5 button and it was my save (the one that started after the window of human reaction time + actual saving) that was definitely corrupted. After the borked save, subsequent saves didn't even appear in the save list, so I wouldn't trust the entire game anymore at that point.
I'd have to deliberately test overlapping saving in order to recreate the results and at this point, I'll just not touch autosaves anymore and hope for the best.