Ring Video Doorbell Wired voltage OK, but not enough power?

On Black Friday I bought a Ring Video Doorbell Wired. Initially I connected it to the already installed Friedland D753 doorbell transformer (used for my old dumb doorbell). This transformer outputs 8V/1A and the Ring App was complaining in the Device Health that the Transformer Voltage was bad (10V, which is still more than the 8V required in Europe). To get rid of this message I bought a Navaris transformer which outputs max. 8VA: 8V/1A, 12V/0.67A, or 24V/0.33A according to the Amazon listing. After installation of this new transformer, the Ring App no longer complains about the Transformer Voltage in the Device Health (it is listed as good, 28V, in green instead of red), but the App still complains in the main screen of the doorbell: Your doorbell transformer doesn’t supply enough power. We recommend installing a Ring Hardwired Transformer or Plug-in Adapter. What’s wrong? Did I buy the wrong transformator? If so, what should I buy instead?