Oxygen sensor output drops to 0V

I had occasional P0134 code come up on my car (bank 1 sensor 1 no activity detected). I checked the sensor output using OBD2 and as soon as I started driving around 100kmh the output was dropping to 0v. It would usually recover when I stop for a minute or two.
I replaced the sensor and I’m still getting the same issue. I did another test where I unplugged the sensor from the PCM and fed it with a ground directly from the battery – same issue, output dropped to 0v at high speed.

What would be the next step? I understand that oxygen sensor should be producing voltage between 0.1 – 0.9 – in case of any manifold leak is it even possible that the sensor would be producing 0.0 instead 0.1? Not sure if I should look for leaks or replace the sensor again (this time with a genuine part..)

Thanks in advance!