I couldn't find any recent posts about this issue that I've only encountered recently and wanted to bring it back up in case someone has a solve.
As the question states, Illustrator saves automatically when closing, and I'm trying to pinpoint how to resolve it. When the error is occurring, a new document that has been edited won't you to close it without saving the file, and any that are unsaved will automatically overwrite the file without prompting. I found the following thread from 2013, but not sure if it's related as it's referencing extensis plugins.
Sometimes when I close my Illustrator CS6 file it automatically saves without asking me if I want to
I do have some Astute Graphics plugins, and scripts I run, but as it appears to happen randomly, I'm not quite sure how to replicate or begin to try and track down the issue. I work with a lot of files from other users, have auto recovery disabled, but was recently working with a recovered file and am wondering if that could otherwise be triggering it? Not sure if it could still be font related... any help trying to resolve would be greatly appreciated. I'm on MAC OS 10.11.6, and Illustrator 22.1