Has anyone been able to determine the exact bounds of what "publicly available" means? The previous two comment discussions on this topic have devolved into arg

Has anyone been able to determine the exact bounds of what "publicly available" means? The previous two comment discussions on this topic have devolved into arguments on ethics, and not really answered that question. All I was able to determine was, some people consider "public" to be outward-facing (I.e., something like Gmail would not be used for training), whereas others claim that anything that is not e2ee will be considered "public". That's no real help.