Some striders float one block over the lava sea in a shivering form instead of on the surface of the lava when upgraded to this snapshot

I've discovered for some bizarre reason that the striders in the Nether, whether at a standstill or in motion, sometimes float one air block on top of the surface of the lava sea in the form of purple shivering, rather than just "on" that lava sea surface itself in normal form the minute I started upgrading to this snapshot. That's totally strange as is the case in my attached screenshots: