lose away off why half led have near and far

If half of an LED strip or light has a noticeably different brightness depending on the distance from the power source, it's usually because of a problem with the power supply or wiring, causing voltage drop along the circuit, where the LEDs further from the power source receive less electricity and appear dimmer; this is often called "voltage drop" and is more prevalent in long LED strips with high current draw.
Key points about this issue:
Voltage drop:
When electricity travels through a wire, it encounters resistance, causing a slight voltage drop as it moves further along the circuit. This means the LEDs near the power source get a full voltage, while those further away receive a slightly lower voltage, resulting in dimmer light.
Poor wiring:
Loose connections or thin gauge wires can exacerbate the voltage drop issue, leading to significant brightness differences across the LED strip.
High current draw:
If the LED strip draws a lot of power, the voltage drop can become more pronounced, especially on long strips with a single power source.
What to do about it:
Check the power supply:
Ensure the power supply is sufficient for the length of the LED strip and is providing the correct voltage.
Use thicker gauge wire:
If possible, use thicker gauge wires to minimize resistance and voltage drop.
Add additional power connections:
For very long LED strips, consider adding additional power connections at regular intervals to distribute power more evenly.
Check for loose connections:
Inspect all connections along the LED strip and ensure they are secure.