URL's using the IRC protocol are not recognized anymore by the URL BBCODE in 3.2.x (the text formatter library). They do not render and appear as broken bbcodes

[url]irc://irc.freenode.net/phpBB-coding[/url] or
[url=irc://irc.freenode.net/phpBB-coding]irc://irc.freenode.net/phpBB-coding[/url]

Text Formatter appears to support irc protocol:
https://github.com/s9e/TextFormatter/blob/c79e98b41fd5517d79d29d0580f2411cce33d56e/docs/Plugins/Autolink/Synopsis.md#how-to-allow-more-schemes

Appears it is a non-configurable config, and was only set by migration to http, https and ftp:
https://github.com/phpbb/phpbb/blob/master/phpBB/phpbb/db/migration/data/v320/allowed_schemes_links.php#L28