my save from the previous update isn't working, is this intended behaviour?
I think it's a safe assumption it is not, don't you think?
You can blame renpy if you're looking for someone to blame. I never mess with existing call stacks or rename existing source files to prevent those kind of issues, but it needed to go to from ren'py 7.3.5 to 8.1.1 to solve crash issues in the image cache (well, technically it went to 7.6.1 first for that, and then on to 8.1.1 to get slightly better memory management on Android devices that were struggling from the sheer size of it).
Try a few different saves, ren'py has quite a few strategies for trying to patch up load problems, but it seems particularly happy about saves that happen on a choice menu (autosaves usually happen there), or for saves that happened in code where there's a program label nearby (starts and ends of scenes, and the "save your game here" should be good too most of the times in that regard).