I was building an item filter and I used water streams. To align them with the hoppers I used cakes and some walls for having the water in place but when the items collide with the second cake the disappear.

I was expecting to have the items running well without disappearing nor moving from the path...

What I got is that bug.

I tried to reproduce it in another world but in a poor way because I couldn't reproduce it. I tried a lot of things to solve it but there is no way (except changing the system to a hopper system). The only things I think could produce this are the dropper or the water flowing up because when I throw the items by hand this bug doesn't happen.