False positive for `no-unknown-elements` for <svg> <g> <title>

It seems that this does not correctly identify <title> tags inside of <svg> <g>.

Reduced test-case

<svg xmlns='http://www.w3.org/2000/svg'>
  <g>
    <title>My title</title>
    <-- other stuff goes in here -->
  </g>
</svg>

This complains:

no-unknown-elements at #header-illustration > div > svg > svg:title:nth-child(1)):
  Unknown element <svg:title> at line 1766

However, that is valid, see: https://developer.mozilla.org/en-US/docs/Web/SVG/Element/title

This was working before, I just updated a bunch of versions (through html-validator), and it seems this was introduced in 6.6.0 - I would guess in: 51025e1d