This has no reason to be called a bug. It is an incredibly useful feature for things like shulker loaders.
Still valid.
I am on version 1.14.60 and just lost my survival world to this bug. World crashed, out of storage message. Tried to return to the world but it was unable to load. Restarted minecraft and loaded the world, only to find most of the chunks completely gone. The world is only 45mb, I have nearly 100gb of free storage. I'm playing on Android.
This is Working As Intended. Activator rails are intended to eject players and mobs out of minecarts. Powered rails will propel the minecart.