Hello,
markers apply a text hightlight color when background-color is set and only allow specific colors (black, blue, cyan, green, magenta, red, yellow, white, darkBlue, darkCyan, darkGreen, darkMagenta, darkRed, darkYellow, darkGray, lightGray). Shadings are applied to whole paragraphs and allow HEX colors.
Although you could apply hightlight colors in list and paragraph contents, the best approach for your case is using the transparent value applied to the background-color style in ul and ol tags:
$html = '<table>
<tbody>
<tr>
<td style="background-color: #a9d29a;">
<ul style="background-color: transparent;">
<li>ef awefawef awefwef</li>
<li>ef awefasdfsdfsdfwef awefwef</li>
<li>sxdfsxdfxsdfef awefawef awefwe</li>
</ul>
<ol style="background-color: transparent;">
<li>xdtgerg egrser</li>
<li>seyhy7 h7yh</li>
</ol>
</td>
</tr>
</tbody>
</table>';
$docx->embedHTML($html);
Regards.