I was able to do a simple regression process on my back, and can pinpoint that it's Frame averaging that created the problem. I updated on 07/03/19, and used the back without frame averaging on a shoot, came back the next morning to test Frame Averaging.
The first series of images during my testing are all 16 Bit EX or non EX, but all are 16 bit. I am sure during those tests I powered the back on and off several times but all the files are the correct size and are 16 bit.
Later that day I came back to the same location and tried some different angles but had turned off the back. From that point on for the next 500 or 600 frames everything was shot in 14 bit low quality. I always check the indicator showing 16 bit EX or non EX, but never noticed the count for frames remaining had gone up by close to 2x. Once you use frame averaging, this bug is set and stays in place even after the back is powered off, so it's a different type of bug one that appears to have to be enabled by a feature, but once enabled stays in place.
This simple fact, still amazes me that none of the P1 developers, or "Professional" shooters caught this as it had to happen to them also, unless this issue was caused by some last minute tweak to the firmware, on P1 knows that.
I still say, this firmware was NOT released as public beta, after rechecking Phase One's main page and doc's, there is no mention of it being a beta with the all the normal literature about use and risk of a beta. Also I know of no other firmware for a IQ that was released as a Public Beta, if anyone knows of one, please correct me. I am fully aware of IQ firmware in beta being given to an end user (I have had it happen) with an understanding that it is a beta and thus be aware of issues. If Phase goes back and changes their release notes on the this firmware to say it's a Public Beta, then shame on them. It's not in the release notes I pulled down on 07/03/19 or yesterday.
Many may find this is not a big deal, that's their prerogative. Net to me is I would have gone on making this same mistake and continuing to shoot the lowest quality from the back as I did not realize the issue was there until someone else pointed out to me. All I know is what I can see in the files. Like another poster, I had also started to wonder about increases in noise in the reviews of the images, but due to the heat in my location I just wrote it off to the back getting warm. There is almost 100MB of file size difference between the 14bit and 16 Bit Ex, the average 14 LOW res image from the IQ4 being close to equal to a High res 14 bit file from a Nikon Z 7.
For me this is as bad as the bug that was allowed to go out day one on non auto rotation of portrait images. And that persisted for almost 6 months. Auto rotation of a portrait image is basic camera operations 101, if you can't auto rotate you should not be releasing a camera yet.
Paul C