The following two system messages are affected:
"config-unicode-pure-php-warning": "'''Warning:''' The [https://pecl.php.net/intl intl PECL extension] is not available to handle Unicode normalisation, falling back to slow pure-PHP implementation.\nIf you run a high-traffic site, you should read a little on [https://www.mediawiki.org/wiki/Special:MyLanguage/Unicode_normalization_considerations Unicode normalisation]."
"config-unicode-using-intl": "Using the [https://pecl.php.net/intl intl PECL extension] for Unicode normalisation."