HI,
DGX Spark OS currently supports 24.04. As discussed in other threads, you are free to experiment with any OS (including downgrade to 22.04), however it’ll be an unsupported configuration. If you need support with Hardware for RMA, we may require you to reimage it back to a supported OS, as our triage tools are tested only for supported configurations.
Per Ubuntu release cycle | Ubuntu, 22.04 LTS will EOL in 2027 (about a year away), you may want to reach out to ARC-OTA and see what their roadmap is? This maybe more efficient path forward than downgrading and risk missing future software updates, security patches and performance gains.