DataError: value too long for type character varying(30)

[sentry-io]

Sentry Issue: FLAGSMITH-API-50F

StringDataRightTruncation: value too long for type character varying(30)

  File "django/db/backends/utils.py", line 89, in _execute
    return self.cursor.execute(sql, params)

DataError: value too long for type character varying(30)

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...
  File "custom_auth/oauth/views.py", line 60, in login_with_github
    token = serializer.save()
  File "custom_auth/oauth/serializers.py", line 54, in create
    user = self._get_user(user_info)
  File "custom_auth/oauth/serializers.py", line 90, in _get_user
    return UserModel.objects.create(