Reliability: unless you’re multi-bilion customer nobody cares, Google can simply ban your account and they won’t assign a human intern to perhaps reconsider dropping all your data because the effort would never pay
With local storage there is at least one person who cares about those problems. With cloud there is none.
Because of course it just has to be Google that you use for your cloud storage? We can't consider any of the dozens and dozens of cloud alternatives also available with much better customer service involving real humans?
People just tout "lol every cloud provider only has AI support with no humans" - when it's just Google - a trillion dollar company - skimping on user support.
Meanwhile there are dozens of alternatives, small, medium and large where you can contact an actual human and get help. No algorithm will ban your account automatically without the right to object.