The Bugcrowd portion of this story is not something I expected to see. The screenshot of the mail is apparently sent from the "Platform Behavior Standards Team," which means that either Bugcrowd are taking a rather expansive view of their platform standards [1] by attempting to police behaviour outside the platform, or Mastercard are impersonating official Bugcrowd staff.
Neither option is particularly palatable.
[1] https://www.bugcrowd.com/resources/hacker-resources/platform...