In the flagging summary page
/users/flag-summary/<id>, the timestamp that the flag is raised for spam and offensive flags are not shown.
From the hims056's comment in this duplicated question: If you hover mouse icon on "helpful" or "decline/disputed" text it shows same timestamp in tooltip, while in case of "Spam" flag it doesn't show any tooltip.
To make sure this ancient bug hasn't been fixed by the recent redesign, I add current screenshots:
Hovering over regular flag shows the UTC timestamp
Hovering over "helpful" shows the time of handling as a relative timestamp, which is often... unhelpful.
And on spam/offensive flags neither thing appears: