I too have had the same alert running Evolve + theme with the exact same error. Reinstalled the latest version of wp-content/themes/evolve-plus/library/admin/redux-extensions/extensions/vendor_support/vendor/ace_editor/mode-php.js from a freshly downloaded theme bundle and got the same error on Wordfence.
When I mark it as “fixed” and do a rescan the file is marked again as a critically severe error.
Seems like the problem remains.
Any chance that Wordfence can be updated to avoid this false positive?