This is in reference to https://mcneel.myjetbrains.com/youtrack/issue/RH-61476 .
As the image below shows, after _MergeAllCoplanarFaces, the snaps on the arc edge reflect the split-face brep.
Also notice that the linear edge on the bottom is still split in 2. This also occurs in V5 and V6.
MergeAllCoplanarFaces_after_RH-61476.3dm (60.8 KB)