I tried downgrade procedure according to the instructions for TFTP software.
I used IPC_G3_EN_STD_5.5.131_210120.zip
After starting tftpserv.exe I only have :
2022-11-25 20:32:29] TFTP server [192.0.0.128] initialized
TFTP server didn't find the camera. Not jump to the testing device step :(...
After researching it seems the solution is to go back to
IPC_G3_EN_STD_5.5.131_210120.zip
It's an older version than the one that came on the new camera (Firmware V5.5.801 build 210727 arrived on the camera)
The downgrade procedure is simple according to the instructions:
"...
TFTP Automatic...
This is my first Hikvision camera.
I bought the camera DS-2CD2646G2-IZS(2.8-12mm) primarily for sharing via youtube (RTMP protocol)
Firmware V5.5.801 build 210727 arrived on the camera
From the page...