Okay, so one day I hoped on osu! then, I was playing a map, but all of a sudden, I held down my singletap key, then that key was singletapping like 300BPM. I have an unlisted video, it'll explain more about the problem, and singletapping.
Video: https://www.youtube.com/watch?v=kFV3kyaLahk
osu! version: Stable 20190207.2 (latest)
Video: https://www.youtube.com/watch?v=kFV3kyaLahk
osu! version: Stable 20190207.2 (latest)