This bug let's water float, it won't flow away, not even sponges work on it. It isn't a raw visual glitch, as it still acts like water when entering it.

Video that shows how to reproduce: https://youtube.com/shorts/N7PxGKVjJw0 (file exceeded size limit) 

This might also work with magma blocks instead of soul sand. The bug was found by me and the video was made by me.