The Polkadot XCM protocol, designed for cross-chain communication, faces message loss risks during parachain congestion. When parachains are overloaded, XCM messages, handled via HRMP or XCMP, may overwhelm queues, especially in HRMP, which stores messages on the Relay Chain, causing resource strain. Congestion can lead to delayed or dropped messages if queues exceed capacity, particularly for parathreads with limited processing. XCMP aims to mitigate this by enabling direct parachain communication, reducing Relay Chain dependency. However, without proper rate-limiting or filtering, congested parachains risk message loss, impacting interoperability. Developers must implement robust queue management and prioritize critical messages to minimize disruptions, ensuring reliable cross-chain interactions even under high network load.