As already mentioned in a comment in #2718, a simple WordPress search for "paragraph" or "core" or "image" (if an image was added) shows unexpected results:

example.com/?s=paragraph

Gutenberg serialization markup leads to unexpected search results with above and many more keywords and keyword parts like para, graph, text, but, butt, button, cat, ate, categories, code, over, cover, form, head, ding, html, late, latest, post, list, quote, tor, table, ...

WP 4.9.1, Gutenberg Plugin 1.8.1