This is something that has been annoying for years with all kind of conveyor belts from all mods since 1.4.7. It's very common for players to have a passive loot magnet system to automatically pull all item entities to them and loot them, making a conveyor sorting system unusable at it pulls all items out of the conveyors.

For a mod dedicated to conveyors (or if you're making a new mod with them), i feel it would be an awesome feature to finally have something that blocks this and make item entities carried by the conveyor stick to it no matter what kind of item magnets/collectors peoples have around.

I don't know much on the coding side but ideally, some kind of internal inventory for conveyors would do it as well as reduce server issues (as item entities can be costly), so you can still see the items move around but they're not technically there and can only be interacted with inventory management systems (pipes, input/ouput on machines, etc).