EC2 migrated off Xen around ten years ago. Only really old instances should be using Xen or Xen emulation.
[ec2-user][~]$ hostnamectl
Static hostname: ip-x-x-x-x.ec2.internal
Icon name: computer-vm
Chassis: vm
Machine ID: ec2d54f27fc534ea74980638ccc33d96
Boot ID: 6caf18b7ed3647819c1985c11f128142
Virtualization: xen
Operating System: Amazon Linux 2023.5.20240903
CPE OS Name: cpe:2.3:o:amazon:amazon_linux:2023
Kernel: Linux 6.1.106-116.188.amzn2023.x86_64
Architecture: x86-64
Hardware Vendor: Xen
Hardware Model: HVM domU
Firmware Version: 4.11.amazonhttps://www.theregister.com/2017/11/07/aws_writes_new_kvm_ba...
It could be that it's not all over and tied to specific machine types still, or there's something they've done to make it report to the guest still that it's xen based for some compatibility reasons.