@J3bus 

Hi,
The latest firmware(1.1.9) of the Tapo C220 still supports the RTSP/ONVIF protocol, we don't have the instructions to downgrade the firmware, and it is also not recommended to do that. In this situation, you can refer to the instructions below to troubleshoot based on the latest firmware, and send me the test results of the below steps for further analysis.
What can I do if fail to stream the Tapo camera via the RTSP/ONVIF protocol?

Note: If you have not tried to change the camera account on the Tapo app> Camera's Device Settings>Advanced Settings>Camera Account page, you may change the password to a new one without special characters for a try.

Best Regards

  @J3bus 

Hi,

The new firmware generally resolves some issues in the previous firmware and improves the device's performance. Therefore, we recommend using the latest firmware on the camera. Additionally, the Tapo C220 V1, 1.1.9 firmware has not introduced changes to the RTSP/ONVIF-related protocols. The functions available in the old firmware are also supported by the new firmware, so it is advisable to troubleshoot on the latest firmware for your issue.

If you are unable to control the camera through the ONVIF connection on Home Assistant, could you please describe the specific problem in detail for further analysis? Have you tried using other apps/programs, such as iSpy or VLC, for comparison testing?

Best Regards