I didn't know I needed to restart my phone after deleting data and cache.
So I tried to remove google account, delete cache and data of google service framework, google play service, google play.
But when I restarted my phone and logged in to my Google account again, I found that "Device not certified" is still displayed in the google play store.
According to MIUI.eu's instructions, the play store should be authenticated:
https://xiaomi.eu/community/threads/miui-12-0-12-1-12-2-12-5-stable-release.56191/#:~:text=Play Store Certified I don't know why my device is not certified