I hovered the mouse over the deleted message by tripleee, whose content used to be
:46713033 still up
Well now, message 46713033 is highlighted. But it shouldn't. The message that refers to it is deleted already.
I've confirmed that any user (including anonymous users - unlogged-in) can see the highlights, after page refresh.
Note that this is not a duplicate of Deleted chat messages still show links if they refer to another message, as that one is a bug report that has been considered by design, this is a feature request asking that the design be changed.