jQuery 2.x is no longer maintained and contains vulnerabilities that could lead to security issues in add-ons. Effective immediately, the validation process will warn you if jQuery 2.x is found during the submission of a new version or add-on. After September 1, 2018, no new submissions using jQuery 2.x will be accepted.
We need to adjust CatBlock to use jQuery 3 if we don't already.
Email from Mozilla:
We need to adjust CatBlock to use jQuery 3 if we don't already.