So these LOD blending issues occur on smaller scales as well. I have been in several locations, on foot and in SRV, where the next patch of ground, some three-to-five metres ahead of me, sticks up like sidewalk kerbing (I guess at least that confirms suspicions about what the purpose is, of the patches having that vertical edge

).
If I walk closer, the heightened area settles down, and gets refined, seaming together with the one I'm on- If I back up again, it raises back up from the ground, in a very consistent, deterministic manner, regardless of which LOD blending setting I've got (supposedly the setting only affects distant LODs, anyway, with full blending always being on nearby, not allowing for the "pop-in-y" "off" option), and regardless of how long I stand around waiting for terrain-gen to get all nearby patches to same density level.
Other than being an issue between two terrain patches at very different detail level, which may have quite different profiles to parts of a hill slope, It may be that this is more likely to happen where you have some local POI elevation modifier, such as guardian earth mounds, or crash site gashes/flatteners - I seem to see it more at such places. Maybe there could also be a rounding error, or floating point (...or even integer, given we're now dealing with bitmaps) precision element to the matter...
EDIT: I guess this could also likely be what causes the unsightly new big blobby pixels along ground patch seams on the scanner...