using ImageColumn with data:image

data:image/png;base64,iVBORw0KGgoAAAANSUhE.....

public function getImageUrl(?string $state = null): ?string
{
  if (filter_var($state, FILTER_VALIDATE_URL) !== false ||
      // added
      str($state)->startsWith('data:')
) {
        return $state;
}