Hello   @onvifuser 

• If ONVIF does not work, you could try to factory reset the camera and test ONVIF stream again.
• Check if you have enabled SD card recording & Tapo care as well as using ONVIF: Q3.4: Why can’t I use Tapo Care, SD card, and NVR at the same time?

As far I know the firmware is particularly to adapt to Hikvison NVR and solve ' language mismatch ' error, other than that it should be the same as the new official firmware. 

If still the same, can you share more details for ONVIF streaming no longer works, what  software do you use and its version, the error message, try to collect camera log, thank you. 

  @onvifuser thank you for sharing the progress, glad to know factory reset help to solve the problem! Sometimes if there are multiples Onvif / stsp requests the camera can be overwhelmed, factory resetting helps to old settings on the cameras and make it work again.