Currently pagure/templates/_render_repo.html ends its success function for the activity lookup with:

if (data.activities.length > 0){
// ...
else {
  $('#user-activity-body').append(
     '<div class="list-group-item">No activity recorded on that day</div>'
  );
}

With that .append() being a bit too effective, because every time you click on a day with no activity, an additional "No activity recorded on that day" message is added below the existing one(s), growing the list ever longer.

Worse, those messages aren't cleared out even when a day with activity is clicked on, nor does closing the Activity list using the × in the upper-right corner — the built up "No activity..." lines return when the list reappears. Only reloading the page flushes out the list.