See also T86453: Cannot add url values as an anonymous or unconfirmed user, which only disable it in Wikimedia production and per https://noc.wikimedia.org/conf/highlight.php?file=Wikibase.php, currently captcha is disabled only in item and property namespace (but not lexeme or mediainfo).
This is only a stopgap measure, applying to both WMF production and 3rd party Wikibase installations, until T87854: allow showing captchas on Wikibase is fixed. Note if we disable captcha in entire entity namespace (not only entity edits) unconfirmed users can add arbitrary content to Commons File description pages, which may open a floodgate of spam.