Before assuming this is a bug, try the form with a genuinely unused email and a correctly-formatted phone number, including a real country code. In at least one case this exact error was consistently reproduced with fake/malformed test values and real area codes, and resolved as soon as a properly-formatted, previously-unused combination was tried — strongly suggesting the form's validation and duplicate-detection logic was doing its job, not malfunctioning.

If it still fails with genuinely valid, fresh test data, that's worth reporting as a real issue rather than retrying endlessly with throwaway values.