It’s because Down Detector works off of user reports rather than automatically detecting outages somehow. So, every time a major service goes down (whether infrastructure like AWS or Cloudflare, or user-facing like YouTube or Facebook), some users will blame Google, ISPs, cellular providers, or some other unrelated service.

Some google sheets functions aren't updating in a timely manner for me. Maybe people google as a backup for aws and they have to throttle certain service from a higher load