Yes it looks like dead pixels on the sensor. To be absolutely sure it is the sensor that fails, you can try and look in a DNG file that must also contain the same dead pixels.
If you cannot find them in the RAW file, there is an error on the software you use on the file, possibly in Anafi FirmWare.
If your SD card is too slow, it will not give dead pixels on your picture but instead give an error message in FF6 that your SD card is too slow.
Regards, Leif.
