The security Issue is one of the most sensitive, especially if it concerns payment systems. Because of the promised ease and convenience, the developers have to take additional responsibility and obligations.
To protect users from theft of money, and claims it is Google disabled Android Pay on devices with an unlocked boot loader.
Earlier Android Pay not only worked on devices with active root. However, even just an unlocked bootloader is a security vulnerability smartphone and data. Such a measure is a requirement of security not only Google, but also of banks-members of payment system.
Now fans of deep customization and third-party firmware put before a choice: rejection Android Pay or waiver of a game with openness and system settings.