The process to reproduce the bug is already recorded in the video:

https://youtu.be/lMoF-iN4NSU

I didn't use sound addons, only changing settings in SHIFT-A menu.

How does one use 24bit sound in LFS?

Why would you do that, when all LFS sound samples are compressed and have a much lower bit rate anyway.

OK, I see. It's 16bit 44100Hz in my Windows setting, but how it matters? I have tried 24bit setting on another audio device but the bug still exists.

By the way, I found "Tone variation" is the key factor. You can reproduce the bug by simply setting it to 1.00