I used the simplest trick in the book. Since we have btop installed (a more advanced and pretty version of tools like top or htop), I was just able to run "btop" to get into its interface.

From there, you can see which CPU the system is using in the top right. Since it's a EPYC CPU, but we only have 2 threads, it goes without saying that we're in a VM since there is no AMD EPYC CPU with only 1 core with 2 threads.

Alternatively:

12:55:11 leo@group-20 ~ → hostnamectl 
 Static hostname: group-20.internal
       Icon name: computer-vm
         Chassis: vm 🖴
      Machine ID: 471f9f9a79d9821160cd1849069e648a
         Boot ID: 3621b630db6a4e0f8b8ba3269550325a
  Virtualization: kvm
Operating System: Ubuntu 24.04.4 LTS              
          Kernel: Linux 6.8.0-111-generic
    Architecture: x86-64
 Hardware Vendor: QEMU
  Hardware Model: Standard PC _Q35 + ICH9, 2009_
Firmware Version: 2024.02-2ubuntu0.8
   Firmware Date: Wed 2025-12-10
    Firmware Age: 6month 1w