Why is my phone charging slower?

I've built an extension of my charging cable to my bed so I do not always have to get up.

This extension I have connected to my LEDs, since they were already available anyway.

The following circuit illustrates this a bit:

As a power source I use the adapter of the Huawei Nova 2.

This provides 1.2 A and 8.95 V when the phone is locked. When the phone is unlocked only 0.6 A and 4.96 V.

Why does not he do that by extending to the bed? The LEDs are of course switched off.

Every cable, no matter how thick, has a certain resistance… This can drastically lower the current / voltage even in such "short" ways:-)

Cables have a resistance (line resistance, cross-section, material and length-dependent).

With USB it is often difficult with more than 1m.

Since you already made, you can probably also solder. One solution might be to add a really thick cross section to the bed and then attach a USB socket where you can plug in a short standard charging cable.