Full Fuel Injection at Partial Throttle

While browsing, I came across the following comment in an old thread titled "TDI engines for towing":

Quote:

If the reading in the same RPM range barely increases or doesn't increase at all when accelerating fully, the engine is effectively running at full load, even if the accelerator pedal is only partially depressed (at low RPMs, the full injection amount is already required with relatively little pedal movement).

(1): So, is it essentially being manipulated using the accelerator pedal curve?
(2): Are there any diagrams available for this topic?
(3): What are the reasons for this behavior?

Greetings, Klaus.

G3 AFN, 200,000 km.