When riding a srtider through the lava, I'd expect that the ridden strider would push through the other striders, following basic entity collision behaviors.

But instead, the strider began walking up on top of the other striders, and in doing so, the strider you're riding begins dying as if it was suffocating. Should this happen in survival mode, a player can easily lose their stuff to the lava if they aren't equipped for that to happen.

This can be done by riding and controlling a strider like normal, then find a pack of wild striders in a lava ocean. Start by moving your strider towards a baby strider and you'll notice that it'll climb on top of it as if it were walking up stairs. And because you're holding an item that attracts other striders, you can then possibly walk on top of adult striders. Occasionally, your strider would get stuck, and your player would start glitching into your strider. Meanwhile, your strider starts dying and the sound "Something trips" begins playing each time it gets hurt. The same behavior can be achieved on land as well, but your strider won't be harmed.