Depth texture tiling artefacts on T6xx?

Hello Mali devs,

We are are observing what appear to be tiling artifacts when sampling a depth texture after it has been rendered as part of a water murk effect. The particular sequence of operations is:

1) Render main scene to depth/color texture.

2) Render water murk (sampling depth rendered in main scene) with depth buffer disabled and frame buffer set to colour only.

3) Resture depth/color framebuffer and render rest of the scene.

It appears this is somehow timing related as the artifacting varies based on camera angle/framerate. I've attached a screenshot showing these artifacts taken on a Mali-T628 device.

Has anyone else observed this? Anything in the sequence of operations described above that may be incompatible with TBDR?

Thanks!

Stephane