As you can see from the screenshot, there are no files on My Drive.
But the quota of My Drive is 4.7 GB used.
When I click Settings->View items taking up storage, the webpage returns empty result which takes up the 4.7 GB storage.
Reproduce: upload some files to My Drive, then move them to one of Team Drives. But I cannot reproduce every time.
This status has lasted for several hours. Maybe not the backend cache problem?
I've also rechecked the differences between files moved from My Drive and files uploaded directly to Team Drive. Nothing useful information.
Why there are invisible files taking up storage of My Drive?