JetPack Protect gives false positive about tracker cache file

[diosmosis]

See https://wordpress.org/support/topic/jetpack-protect-warning

The warning is due to malicious domains appearing in the tracker cache. These URLs come from the referrer spam block list. While the file is harmless and the warning can be ignored, it may scare non-tech savvy users and make users think twice about using Matomo.

If possible (and it may not be) we should try to keep this false positive from occurring.