Per https://ask.clojure.org/index.php/10724/no-metadata-on-clojure-1-9-map-literals

Maps written using the new #:default.namespace{,,,} syntax don't get file positions attached as metadata.

Given this setup code

(require '[clojure.tools.reader :as reader])
(require '[clojure.tools.reader.reader-types :as reader-types])

(defn sample [s]
(with-open [r (java.io.StringReader. s)]
(meta (reader/read (reader-types/indexing-push-back-reader (reader-types/push-back-reader r) 1)))))

this edn literal fails to get parsed with positional metadata

(sample "#:ns{ :key :val }") ; => nil

unlike those two, which get their positional metadata as expected

(sample "{ :key :val }") ; => {:line 1, :column 1, :end-line 1, :end-column 14}
(sample "{ :ns/key val }") ; => {:line 1, :column 1, :end-line 1, :end-column 16}