Bundle fills with 4x multiplier on small stack items such as Snowball

When using a bundle with small stackable items such as 'Snowball' the bundle has a 4x multiplier, from the various sources, they should hold up to 64 items.

https://www.minecraft.net/en-us/article/bundles-are-making-a-comeback
What are bundles?
A bundle is an item that can hold other items! Eager to test this new concept of stuffing stuff into other stuff, I grabbed my trusty rucksack and tried to squeeze 64 cobblestone blocks into it. Unfortunately, that functionality is reserved only for bundles – which allow you to store up to 64 of an item (provided it can be stacked to 64!).

Whilst it is expected behaviour to not carry 4x 16 Snowball within a Bundle, it should not fill prematurely from the lower amount stackable items.

Here are some of the following examples.
10 Snowball
16 Cobblestone
8 Sweet Berries

14 Snowball 
8 Cobblestone

15 Snowball
2 Cobblestone
2 Sweet Berries

From the 1.21.40 release notes.
A Bundle only fits one stack (usually 64 items) but it can be a mixture of many different item types

An expected result would be.

32 Cobblestone
16 Snowball
8 Enderpearl
8 Sweet Berries

Is the Bundle behaviour only to be the consolidation of the total slot value?