假如已经购买Google Workspace， 但是在Gmail邮箱有这个提示，那么不用慌，是Google后端的一个bug。（当然，你未购买Workspace，那么得按照建议去清空间出来）
Chat with Workspace support agent:
Google Workspace Support: As per checking these issues from the back end system, it seems like there is an on-going issue with the storage that triggers this prompts to the accounts of numerous customers.
Google Workspace Support: This bug is now being looked at by our developers. This issue should be resolved in 24-48 hours. Can you try to send outbound emails to one of your personal email addresses? Once you’ve received it from your personal email address, try to reply to it to check if you will be able to receive it.
Google Workspace Support: I’ve double checked your account here in terms of storage and nothing to worry as you have a lot of available storage.