Hi Foil,
You can use the Windows 365 Connection Quality report in Intune to see connection performance over the last 7 or 28 days. The most important metric for this case is Round Trip Time (RTT), which measures the delay between the user's device and the Cloud PC. Higher RTT usually means more noticeable mouse lag and slower response times.
Since your users are in Southeast Asia and the Cloud PCs are hosted in US East, consistently high RTT values may indicate that geographic distance is affecting the experience. The report also shows bandwidth and UDP usage, which can help determine whether the issue is network quality or simply the hosting location.
If the data shows persistently high RTT across affected users over time, that would be strong evidence to support moving the Cloud PCs to a closer Azure region to improve responsiveness and reduce mouse input lag.
Harry.