... or "messed up gravity effect on horses".

I was having fun of using self scroll teleport through summoned horse.
(Like because it's the only way to self scroll teleport without consuming teleport scroll; and I like it)

But accidentally stepped into hidden rune that I was casting.
Simply launch upward>timer>gravity>time extend
That killing almost everyone...
But not my horse I was riding.

Being up in sky
I was thinking "Here's comes death"
And Waited... a little bit too long.
Then released that my skeletal horse can't normally fall here.

It just stuck in air.

There was "ars elemental" installed, but the only thing from here were a skeletal horse.
Simple summoned horse works same in air with gravity effect, tested.

I'm not sure about horse without passengers, but I will test it soon.

Hope that information would be helpful.

... does...
That happens because one who riding mob doesn't having gravity effect..?

It looks like it's about riding...