WordPress core file modified | WordPress.org

I received a message that a WordPress core file was modified: index.php. This happened the day after I (1) moved to a new hosting provider and (2) followed the step suggested by the Wordfence plugin to enable the Wordfence Web Application Firewall. Could this have anything to do with one of these events? Otherwise I am not sure how it happened and whether it is bad news or not.

Thank you!

Screenshot of changes to the index.php file:
https://pasteboard.co/St0tIwkyCo46.png