High Power Consumption in S0 Standby Mode (same as Idle ~40W)

I have an unusual issue with my Dell Tower Plus EBT225O power consumption in modern standby (S0). In this state, the system draws nearly the same amount of power as when idle, around 40W (according to a smart plug.)
As a workaround, I use an application that triggers a full shutdown whenever inactivity is detected. This behavior seems abnormal, as my understanding is that S0 standby should substantially reduce power usage compared to idle, yet in this case, there is no noticeable difference.

More detailed numbers:

|-------------------------------------|------------|
| State                               | Power draw |
|-------------------------------------|------------|
| Idle, session open                  | ~42W       |
| Modern Standby (S0), session open   | ~35W       |
| Modern Standby (S0), session closed | ~18W       |
| Idle, session open, standby disabled| ~37W       |
|-------------------------------------|------------|

• Has anyone else experienced this issue?
• Is this normal behavior for this model ?