these rules has been changed https://osu.ppy.sh/wiki/en/Ranking_criteria/Metadata#:~:text=Only%20songs%20that%20also%20increase%20the%20pitch%20of%20the%20audio%20can%20use%20(Nightcore%20Mix).%20Otherwise%2C%20use%20(Sped%20Up%20Ver.).
tl:dr
if audio speed uped with pitch -> nightcore
if audio speed uped without pitch -> sped up
here's a better audio of this banger song
https://defreeyay.s-ul.eu/7Bmk6Oat no need offset changes, write in .osu from audio.mp3 to audio.ogg in all diffs
title should be
Polaroid (Speed Up ver.) -> Polaroid (Nightcore Mix)
new tags as well, so you just copy them:
malay malaysia malaysian english pop rock sped speed up ver. version KPMY
The marker to signify that the song has been edited to have a higher tempo is "(Sped Up Ver.)"; "(Speed Up ver.)" is incorrect.