Thanks for posting the code that illustrates your issue.
The problem is how the WordFragments work internally, that in certain cases don't add a run-of-text to apply that break. Instead of adding new tags to wrap the contents to use phpdocx_link with line breaks, for your case the best and easiest approach is using a tags (that allows using internal anchors too) wrapping the contents in a paragraph:
<td width="252pt" valign="top">
<b><a href="#7d6a55a24099ef9068ad4bbbc35aa0d1">Maurice Nicolas</a></b> - BioNTech AG<br />
Business Development<br />
P: +1169005827387<br />
C: +1 231-607-8121<br />
<b><a href="#1c6bd954cd94500481cd13cb21fda279">Hans Hansen</a></b> - ABC Capital<br />
PNC Relationship Manager<br />
As you need to apply the anchors to link internal contents instead of external ones, you can set parseAnchors as true when importing HTML:
$docx->embedHTML($html, array('parseAnchors' => true));
Using the previous code your internal links will work with the br tags as needed. You can read about this option on the API page (https://www.phpdocx.com/api-documentation/word-content/embed-html-Word-document-with-PHP) and the introduction doc about HTML to DOCX (https://www.phpdocx.com/documentation/introduction/html-to-word-PHP).