There are occasions where L is useful like maintaining speed going down hill, but D should be selected for best general driving efficiency.
Both D and L will engage some regen as soon as you remove your foot from the accelerator. However, L forces a much higher level of regen as soon as you take your foot off the accelerator than “D”.
Regen is inefficient and I try to avoid it and coast as much as possible. L may have the tendency of shuffling the car’s kinetic energy into the battery and back in response to every positional twitch of your foot on the accelerator and would chock up higher conversion losses. Stepping on the brake with light to moderate pressure will still achieve full regeneration (no friction brakes) and it allows you to better control the timing and amount of the regen.