Thank you for contacting the support.
There are a few things to notice here:
1. The functionality of the above file is not getting executed via Rank Math.
2. Even though the file was included in the plugin, we were not using it for a long time, so this vulnerability does not affect Rank Math users.
With that said, we released an update sometime back. Please update the plugin to the latest version, so you do not see the above error.
Hope that helps. Please let us know if you need any other assistance. We are here to help.