“This bug was a buffer overflow which caused coreboot firmware memory to be overwritten by the TPM measurement log, keeping the S3 suspend method from working properly.”
One buffer overflow forced System76 off S3 suspend and onto S0ix, and S0ix needs Intel’s Management Engine running. Fix the overflow, go back to S3, switch the ME off again. Intel ties a basic power feature to a closed coprocessor that sits under your operating system. It took a small vendor patching coreboot to give buyers the choice.