Prior to the Beanstalk Community Multisig (BCM) custodying ownership of the Beanstalk contract, Publius custodied the contract.
When there was a need to Pause Beanstalk in the event of a dangerous vulnerability, a BPP was proposed to determine whether the Beanstalk DAO would prefer Publius to patch the vulnerability themselves or to patch the vulnerability via BIP.
There was only ever one BPP. BPPs have been deprecated—the BCM can Pause Beanstalk according to the process outline here.