I'm stuck using Copilot for work, and for 3-4 months I began every prompt with 'Do not comment or offer an opinion on my query' and eventually Copilot stopped with the sycophancy.
Now I'm actively working on deprogramming myself of the notion of speaking to it as a human and making a point to treat it like an old-school MS-DOS ish OS and give it commands instead of being conversational, because it's important to remember that this fucking thing is a computer program.