John Rumm wrote:

Also, as commented at the time, the Aldi power meter does not look like
it understand power factors. So lightly loaded switched mode supplies
(which often exhibit very poor power factors) could over-read
significantly.

Have you seen the Aldi power meter?
It actually seems quite sophisticated,
certainly more so than the Maplin meter (which I have also used).
Eg the manual is difficult to follow ...