[subbu@earth:~/work/wmf/mediawiki] echo "[[<div></div>]]" | parse.js --trace peg --normalize
0-[peg] | ----> [{"type":"SelfclosingTagTk","name":"wikilink","attribs":[{"k":"href","v":["<div></div>"],"vsrc":"<div></div>"}],"dataAttribs":{"tsr":[0,15],"src":"[[<div></div>]]"}}]
0-[peg] | ----> [{"type":"NlTk","dataAttribs":{"tsr":[15,16]}}]
0-[peg] | ----> [{"type":"EOFTk"}]
<p>[[<div></div>]]</p>
[subbu@earth:~/work/wmf/mediawiki] echo "[[<div></div>]]" | php maintenance/parse.php
<div class="mw-parser-output">[[<div></div>]]
</div>< is not a valid title char so [[<div></div>]] could never be a wikilink.
So, either a TSP or a wikilink handler issue, if not a tokenizer precedence issue.
Found in https://en.wikipedia.org/api/rest_v1/page/html/Vitamin_D, specifically {{VitaminDSynthesis_WP1531|highlight=Calcifediol}}