When you have efficiency 5 netherite pickaxe and haste II, quartz becomes insta mineable. This is the case for all quartz except smooth quartz, smooth quartz stairs, smooth quartz slabs, and quartz slabs. Every other version of quartz is insta mineable except these ones. While creating a spleef map I had to make some annoying compromises because I couldn't use smooth quartz.

Video showcasing bug: https://streamable.com/xesbk6