You're not flop, regression is flop! (v6)

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Across
  1. 1. 6 tennis games
  2. 2. App where people lie about being 6 ft
  3. 4. 6th most-populated US city
  4. 6. Six __ Slam
  5. 8. Cute, drug-dealing 6-yr-old dog
  6. 9. Universal's less fun competitor: Six __
Down
  1. 1. Brainrot number after 6
  2. 3. __3sixty
  3. 5. 6th president and first nepo baby
  4. 7. Greek mythology river