Bumping posts by adding tags

I went back to add tags to some of my old posts, and it looks like it bumped them to the “Latest” panel. But for others it didn’t do anything. Does anyone know what’s going on here? I’d like to be able to add the metadata without bumping every old post to do so, but it seems like it’s not even predictable as to when it does happen.

Do you have a couple of examples where that happened?

and

got bumped by adding the diffeq tag.

and

are two of many that did not get bumped

As far as I can tell the main difference is that the not bumped post,
didn’t have any prior tags. The one that got bumped did have a prior tag.
Can you report this to meta.discourse.org?