Hello, so I witnessed a very strange thing about Skeleton Horse trap (4 ridable skeleton horses and 4 skeletons riding them). So I was on hard difficulty, it was thunderstorm and I went for some charged creeper hunting. I got about 10+- creepers following me and that was the first night, every lightning was missing the creepers. The other day (minecraft day), it was again thunderstorm and I went for charged creeper hunting again. So that second minecraft night I got about 15 creepers following me and I was waiting for that lightning. Suddenly very very strange thing happened which I think is a bug. So the group of about 15 creepers was struck by lightning and the 4 skeleton horses with 4 skeletons were spawned. Though the creepers were unaffected by that lightning strike. This is very strange because I sincerely think that lightning needs to strike a horse to spawn the Skeleton Horse Trap. I didn't record this thing because I didn't know it will happen, I just wanted charged creeper but it was a surprise to see Skeleton Trap popping out from that creeper group that was been striked.
Here's the screenshot now because I don't have any from earlier. Ignore the Mushroom Island, the Skeleton Trap occurred on Plains biome, but I've transported them to Mushroom Island.

• Long story short: So the creeper group was struck by lightning and suddenly the Skeleton Horses with Skeletons (Skeleton Trap) popped out of the creeper group, the creepers were unaffected. How can Lightning strike a creeper and spawn a Skeleton Horses? There wasn't any horses nearby at all. I think there needs to be one horse that can be struck by lightning and then spawn a Skeleton Horses (Skeleton Trap), which is not a case with my event.

P.S. I tried to describe this as precisely as I could.