Not true. When you create a new ChatGPT Chat project you decide whether it shares its memory/files with the rest of the workspace or if it should be fully isolated.
TIL. There is indeed a switch in the settings, which for me is set to "default memory".
Not sure if it always asked for this and I just forgot, I made all my current projects back when the feature was new.
FWIW, I enabled that feature now, and it still answer based on discussions in other projects. (It’s pretty obvious given the very different contents of each project.) Perhaps it might be a caching issue, that it somehow doesn’t rebuild its memory just because you flip a switch, but just stops learning new things from other projects?
That’s very possible and in fact until recently you couldn’t enable or disable that feature in an existing project, it was only configurable when creating a project. And for some time you couldn’t even move in and out conversations from a project configured with project-only memories/files