rfmjoe

tested this (https://raw.githubusercontent.com/joomla/joomla-cms/81b7afeda08c2dce8aec9b34267220d086e6af0b/plugins/system/sef/src/Extension/Sef.php) successfully on a live-site.

as far as i know, joomla core hat no "canonical" link feature built in. So this might rely to the plugin/component you are using maype?