The generated TimeLine.html does not seem to escape HTML so e.g. below results in a popup "123" when viewed in a browser (or in a TeamCity tab):
<div class="passingtest"><div style="display:inline;margin-left: 10px;"><i data-feather="check"></i> MiscFixtures.GetReminderTextReturnsHtmlEncodedMessage("test reminder")</div></div>
<div class="passingtest"><div style="display:inline;margin-left: 10px;"><i data-feather="check"></i> MiscFixtures.*</div></div>
<div class="passingtest"><div style="display:inline;margin-left: 10px;"><i data-feather="check"></i> MiscFixtures.GetReminderTextReturnsHtmlEncodedMessage("test reminder<br/><script>alert(123);</script>")</div></div>