There is at least one report of Chase shutting down all of the accounts of a Chase Aeroplan cardholder that ‘abused’ the PYB feature of the card. For those unfamiliar Chase Aeroplan cardholders can redeem Aeroplan miles for 1.25¢ against travel charges on the card. You’re not limited to using Aeroplan miles that are earned on this card and there is also no cap for this calendar year (from 2024 onwards there will be a cap of 50,000 miles). The cardholders whose account was shut down did redeem 5,000,000 miles not earned on the card towards Chase travel purchases so not a huge surprise but worth mentioning for those using this card feature.
Source: doctorofcredit.com