This only seems to happen when those characters are character entities in the formatted_body (not when it's a simple plain message, for example). The content of the event in the screenshot is:

{ "body": "<ServoFire> I know you can set that to happen in Cura when you slice the file with the print order option", "format": "org.matrix.custom.html", "formatted_body": "&lt;S​ervoFire&gt; I know you can set that to happen in Cura when you slice the file with the print order option", "msgtype": "m.text" } 

and it renders as expected (using < and > instead of &lt; and &gt;) when viewing the event in the room itself.

Element Web develop (c5f5330-react-d203e8f1294a-js-dc64c34ccb82) on Firefox 88.