Reproduction steps:

• run PSI test on "https://amp.dev"
• results:
  

As an aside, AMP pages across the board seem to be scoring less on the PSI report, and LCP's seem to fail the 2.5s threshold across the board. Not reporting this LCP note as a bug, but it is relatively alarming to those who spend a lot of time optimizing their pages on AMP. Google Search Console also seems to report drastically lower LCP results in "Web Vitals" report (2.x seconds as opposed to 4.x when tested directly via PSI).