There's a bug in Vulkan drivers for Adreno 500+ (not sure exactly which model is the first affected) where if you draw with a stencil writing mode set, like VK_COMPARE_ALWAYS and VK_STENCIL_OP_REPLACE, and discard some pixels in the fragment shaders, the stencil value will get written even to the pixels that should have been discarded.
I have a very easy repro.
Or any later than v1.7.5-308 from the same buildbot.
Start it, make sure that Backend is set to Vulkan in graphics settings, and go to Settings/Tools/Developer Tools/GPU Driver Test.
You'll find that some of the green text doesn't print correctly on Adreno 540+ (and possibly some earlier models) . This is a sure sign of the bug. On all other GPU families, all the green text prints correctly.
A fix would be nice.
(This is really the same bug as https://developer.qualcomm.com/forum/qdn-forums/software/adreno-gpu-sdk/... , just now with a repro and simpler setup)