Is your feature request related to a problem? Please describe.
When using the item collectors to pickup lots of items at once, for instance with a platform of sieves all working together at once, it is always annoying to accidentally be picking up loads of stuff while walking through the area. You'd use the item collectors so that you don't have to pick up anything, but if you're in the range yourself you as a player are able to interfere.

The reason this happens is that the order in which entities are ticked, is undetermined and can cause the player to be ticked before the item collector within the next cycle, in case the item collector happens before the block that spawns the items.

Describe the solution you'd like
To be able to really always pick up items before the player does, one way would be to prevent the spawning of items altogether and to insert them into the attached inventory straight away. This is how another mod did it before in 1.12, presumably (probably Dark Utilities, with the Pearled Ender Hopper).