We use patternlab-php-core and edition-php-twig-standard in our project.
We noticed that since PHP 8.0 the config in config/patternengines.json is missing the class namespaces.
I believe this due to an update to the functionality of the token_get_all() built in PHP function, used in InstallerUtil::findClasses().
The fix may be as simple as updating line 135 to consider the new namespace token types:
if (in_array($tokens[$i][0], array(T_STRING, T_NS_SEPARATOR, T_NAME_FULLY_QUALIFIED, T_NAME_QUALIFIED, T_NAME_RELATIVE))) {