Bug: Toggling a colored tag with number keys doesn't update Date Modified
In 5.0.96.2, toggling a colored tag with number keys doesn't update the Date Modified field. Manually editing a tag in the right pane does update Date Modified however.
There's also this minor issue, which is somewhat related:
https://forums.zotero.org/discussion/79900/minor-issue-related-to-colored-tags
(I haven't checked if this has been fixed in the meantime.)
I agree it should be consistent with dragging to a colored tag, though, and arguably with dragging to any tag. One option would obviously be not to update Date Modified for tag changes at all, but I suspect lots of people do want tag changes to update the date (particularly in groups where tagging is an important part of the workflow), so maybe it just needs to change in all cases…
That editing tags updates the Date Modified was a great improvement in Zotero 5 over Zotero 4. Please don't revert that!
And of course, any field change has the same side effect, so maybe the real point is just that you shouldn't sort by Date Modified while editing items unless you're OK with items jumping around…