The bug
The /tick freeze command stops most player-entity collision interactions such as movement and damage from happening. However, it is still possible to pick up items (which are not on cooldown) and experience orbs in this state.
This may also be the case for arrows and tridents.
How to reproduce
/tick freeze/summon minecraft:item ~ ~ ~ {Item: {id:"minecraft:snow",Count:1}}
Expected results
The item would not be immediately picked up.
Actual results
It is.
Can confirm - it even does this when you're using /give, and when you pick up the item, an image of that item will continue floating in midair until time is unfrozen.