Access blocked: tosheets’s request is invalid

[avilella]

I see this since this afternoon (UK time):

You can’t sign in because tosheets sent an invalid request. You can try again later, or contact the [developer](https://accounts.google.com/) about this issue. [Learn more about this error](https://support.google.com/accounts/answer/12379384)
If you are a developer of tosheets, see [error details](https://accounts.google.com/).
Error 400: invalid_request

Any ideas?