Monospace,Courier, Nimbus Mono PS, Nimbus Mono L<br>
<span style="font-family: monospace;">affiliated affection monospace</span><br>
<span style="font-family: Courier;">affiliated affection Courier</span><br>
<span style="font-family: Nimbus Mono PS;">affiliated affection Nimbus Mono PS</span><br>
<span style="font-family: Nimbus Mono L;">affiliated affection Nimbus Mono L</span><br>

<p>
  In Firefox on Fedora 35 KDE Spin, Courier matches the installed font Nimbus Mono PS,
  but the &quot;ff&quot; combinations are replaced by ligatures which are <em>not</em> monospaced!
</p>