I am running Jenkins 2.387.1 (latest LTS). When I upgraded the ec2-plugin from 2.0.6 to 2.0.7, I found that all Agents were terminated after 10 minutes, which is our Idle termination time, even if a job was running on the Agent. In all cases, Agents were terminated 10 minutes after starting.

When we reverted back to 2.0.6, the problem went away, so this looks like a bug introduced in 2.0.7.
There were 2 PRs in that release, #827, and #825.

The Jenkins job log shows this:

Idle timeout of EC2 (CI-PROD) - Publisher v20230323 (i-0a844c202e5d3ac3d) after 11 idle minutes, instance statusRUNNING
Apr 04, 2023 3:24:40 PM INFO hudson.plugins.ec2.EC2AbstractSlave idleTimeout
EC2 instance idle time expired: i-0a844c202e5d3ac3d
Apr 04, 2023 3:24:40 PM INFO hudson.plugins.ec2.EC2AbstractSlave stop
EC2 instance stop request sent for i-0a844c202e5d3ac3d
Apr 04, 2023 3:24:40 PM INFO hudson.plugins.ec2.EC2RetentionStrategy internalCheck