$width and $height not pointing to correct array index

A solution could be to remove that part of the array, like:

      // Remove the 'improved' part from $style_parts and re-index.
      unset($style_parts[1]);
      $style_parts = array_values($style_parts);

Thanks, Tancredi, for reporting and the Proposed fix
Let us create an MR to quick test then follow up with a quick fix release

I should probably note that this is a Drupal 11 site, in case that makes a difference

Tancredi, thanks for the MR
For sure, to be tested in both Drupal 10 and Drupal 11