The bug allows an attacker to make the TPM record and measure one partition table layout while the firmware and operating system actually use a different layout.

This breaks the trustworthiness of TPM PCR[5] measurements, which are commonly used for:

TPM-based full disk encryption (FDE)
Remote attestation
Secure boot integrity validation

In practice, the system may appear “trusted” according to TPM measurements even though a malicious partition layout is being used.