What sort settings were you using when viewing All? I’ve noticed that when using the Hot sort setting, I occasionally get some random years old threads, usually from lemmy.ml.
I can’t say for sure, so take this with a grain of salt, but I’ve just chalked it up to a glitch in the use of the two settings (all/hot) together. Given the description of how the sorting settings are meant to work from the lemmy docs, I think I may be close to right, but I’m not a dev or anything for it so…Yeah.