Operating system: Windows 10 (1909)
Graphics card: Nvidia RTX 2060
Broken: Presumably all versions including OptiX (earliest tested: 2.82, latest tested: 2.83, 42012493a8e1, master, 2020-03-19)
Short description of error
Random Walk subsurface materials appear significantly less saturated with the OptiX Cycles engine compared to CUDA and CPU, however Christensen-Burley materials render as expected.
Exact steps for others to reproduce the error
Open attached blend file (or add Principled BSDF/Subsurface Scattering BSSRDF with Random Walk to any object). Render with CUDA/CPU, then with OptiX, and compare.