At a minimum, eARC requires that both an audio device and its connected HDMI port support HDMI 2.1. If you're unsure, check ...

The rear panel houses dual Thunderbolt 4 ports, one of which supports PD-in up to 100-watts (it’s a shame MSI hasn't yet embraced Thunderbolt 5 for even faster data transfer speeds), dual HDMI ports, ...