I’ve reproduced this “feature” for Canon R5 (8192x5464) and Nikon Z8 (8256x5504).
The results are the same as for 24MPx D780: DPXD “blocks” are 416x416,
while DP blocks are 1024x1024. So its probably DxO’s compromise between quality
and performance. The feature is seen only at high DeepPRIME.Luminance settings which
nobody sane would use. Hence, to simplify things and maybe for performance reasons (?), DxO didn’t use overlapping regions.
For example, take
“Canon EOS R5 sample gallery: Digital Photography Review”
and set
- DeepPRIME.Luminance = 100
- DeepPRIME.Noise model = -100
- Exposure = +1.0
- Microcontrast = +100
This photo has unexpectedly strong electronic artifacts for an ISO 50k shot,
but nevertheless the blocks are clearly visible.
As for the maze, it can be amplified by ‘Unsharp mask’.
Using also other sliders for the “noise photo”, some interesting textures
can be produced, for which I have yet to find application 
I was trying to get some non-typical random grain patterns.
The grain provided by DxO probably comes from replicating the scan of 7x7mm
film area and the repeating pattern can be quite visible for some films.
Perhaps ‘Agfa APX 100’ and ‘Kodak Tri-X 400’ are uniform enough to use safely.