How Does a Threshold Signature Scheme Prevent a Malicious Node from Submitting False Data?

A malicious node cannot submit false data because it cannot generate a valid threshold signature on its own. It needs the cooperation of $T-1$ other honest nodes to reach the required threshold.

Since the honest nodes will not sign a false price, the malicious node's attempt to submit corrupted data will fail the on-chain signature verification check, preventing the false data from being accepted.