Summary: A recurring donor's card expires and they don't proactively update on their Paypal account (PP currently doesn't have an account updater). The donor doesn't have a backup funding option, and we have set MAXFAILEDATTEMPTS to 3. After the third attempt, the donor gets an email from PayPal saying "Wikimedia has suspended your automatic payments", and it's tricky to restart.
Set MAXFAILEDATTEMPTS to 0 and PayPal will keep trying.