Unusual distortion when using FFR

Tried Unity 2019.3.5 & 2019.3.12
Unity Android package 2.38.6
Oculus SDK plugin (not XR plugin): 1.44

I'm using dynamic FFR as well as static FFR (option on menu). I'm seeing a very strange line "seam" between geometry, although the geometry is continuous.

I've captured using renderdoc and the effect was not present. It is only
present in the headset at the intersection boundary of the lower
resolution FFR areas. It changes between the medium and low res as well.

If I disable FFR the effect goes away. It appears to be related to the distance of the geometry. Closer terrain sections do not show the problem.

I've tried changing the near and far clipping planes, disabling MSAA and Multiview/multipass but it didn't help.