A documented case, wrong in both directions.
One hotel group's Google Ads reported $139,500 in revenue at 6.98× ROAS over a 45-day window. Fourteen of those bookings, worth $21,000, were later cancelled and stayed in the report, while 43 real bookings were never tracked at all: 68.4% coverage. The figure was too high and too low at once, which is why it looked plausible.