Thanks for sharing this @vou. Looks like the query is updated now.
Below is the updated query
#+BEGIN_QUERY
{:title "Broken References"
:query [:find (pull ?b [*])
:in $ ?matcher
:where
[(re-pattern ?matcher) ?regex]
[?b :block/content ?c]
[(re-find ?regex ?c)]
[(missing? $ ?b :block/refs)]]
:inputs [ "\\([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\\)"]
}
#+END_QUERY
Also I had a similar question posted here - not for broken references, but for invalid references: