External SSD heats up on MacBook Air (M1, 2020) with Monterey 12.4.

NNWED wrote:

I'm using WD NVMe 1TB SSD on USB 3.2 (gen2) enclosure.

There is a thread describing similar symptoms, but it was already closed.

External SSD overheating under macOS Mont… - Apple Community

However, it is still occurring after updating to 12.4.

The problem occurs even when just connected and idling, and the cause cannot be determined by looking at the activity monitor.

This problem does not occur with intel macs with High sierra.

What are the possible causes?

Try a more contemporary enclosure or alternate enclosure, alternate cable and compare your results...

WD NVMe USB 3.2 (gen2) enclosure—Software & Downloads - WD Support - Western Digital

if in doubt search the developers website or contact: Support/Help/FAQ/Known issues/compatibility/Updates

Contact a third-party vendor - Apple Support

Contact a third-party vendor - Apple Support

try an different brand external drive and compare your results...

submit your Apple Feedback Product Feedback - Apple