That’s a solid red flag. Start by isolating the shader code in a sandboxed environment so any side‑channel traffic is contained. Use a deterministic compiler flag to eliminate jitter, then feed the fragment shader with known data and monitor the GPU pipeline for timing or power spikes. Apply a checksum or hash to the output texture and compare it to an expected value; any divergence could indicate hidden data. Finally, enforce a policy that disallows shaders from accessing external memory or network sockets unless explicitly signed. Regularly audit the GLSL source for suspicious bit‑manipulation patterns and keep the driver firmware up to date to patch known leak vectors.