To reproduce the issue follow the steps:
1. Create new project
2. Import Standard Image Effects assets package
3. Open "TiltShiftHdrLensBlur" shader
4. "SmallDiscKernel" array is not used to boost performance in the following code (etc. low quality setting)

Expected/Suggested behaviour:
DiscKernel could be replaced with SmallDiscKernel array in Low Quality setting to boost performance for mobile devices.

Reproduced in 5.2.2f1, 5.4.0f3, 5.3.0f4