this question keeps bothering me and i must know. maybe this will help me make a new beatmap? i dont know myself but still i need this question to be answered

In my perspective as osu!mania mapper, long notes represents, well, long sounds. Sustained sound like a long vocal, or long instrument may be represented as those, for the basic. Higher level of mapping may use these for artistic style that I still don't understand either!

haha lnssss star rate go brrrrrrrrrr

sometimes a normal note wouldn't represent the sound well enough and a ln helps express it better