The LEDs can be connected to a PCB in series or parallel circuits. While connecting the LEDs to ensure the same current- series circuits should be prioritized. In a parallel circuit, the same voltage is applied to each LED.
Theoretically, the same current would pass through each LED if they do not have any production tolerances and if a constant temperature of all LEDs is guaranteed. Since this is very difficult to achieve, it may happen that some LEDs succumb to a higher current and will therefore be destroyed.