Canon R7 files importing files pixelate after 100%

I've added a screenshot shot displaying the issue when EOS R7 raw file is opened into Canon DPP application. Unfortunately, I'm not familar with DPP Editing tools. So, the edit is nothing more than Auto and a Curve. 

I'm fairly sure that it's the same issue raised in this thread regarding the Sont A7 IV

https://community.adobe.com/t5/lightroom-classic-discussions/grid-lines-show-in-picture/m-p/13478335#M306386

I don't have a technical explanation and no amount Google searching has turned up more than guesswork and a similar issue occurring with cameras from other vendors. As I state in above linked thread, I have seen similar (see the screenshots) with my EOS R7 when using LrC, ACR, LrD, Capture One, Canon DPP and DxO. In my case, it's 3 files out of close to 10,000. The 3 files were capatured with lens wide open, which is consistent with the other reports I read re Sony and Fuji.  I also found a thread on DPReview where a user had seen something similar. Others in the same thread remarked that the pattern was also present in some of DPReviews own sample files. Unfortunately, I can't locate the thread at present.