The complete rule snippet relevant here is:
Casting some spells requires particular objects, specified in parentheses in the component entry. A character can use a component pouch or a spellcasting focus (found in chapter 5, “Equipment”) in place of the components specified for a spell. But if a cost is indicated for a component, a character must have that specific component before he or she can cast the spell.
If a spell states that a material component is consumed by the spell, the caster must provide this component for each casting of the spell.
First of all, component pouch and focus are mechanically the same, and used "in place of" the listed objects. The non-intuitive, but notable detail here is, that the component pouch does not contain the components listed in the spell, it contains the components needed to cast the spell, when you use the pouch in place of the material component. To verify this, let's see component pouch description:
A component pouch is a small, watertight leather belt pouch that has compartments to hold all the material components and other special items you need to cast your spells, except for those components that have a specific cost (as indicated in a spell's description).
This small pouch itself is not said to be an extra-dimensional space, and has a fixed weight, so it most certainly can not contain 25 feet of hemp rope for Snare, for example. Another example, storing a cup of water for Armor of Agathys in a small pouch seems a bit impractical. The only reasonable conclusion is, that at least some of the stuff in the pouch is different from what is listed in a spell's description, while still being as valid as a focus for casting the spell. The pouch is not some mysterious storage for literally every listed zero-cost material component of all spells. What exactly it contains is left for DM to decide, if hand-waving of "everything you need to use the pouch in place of the material components* is not good enough.
Then there is "But...", exception for components with a cost, which we don't care about in this QA.
Then the second paragraph seems a bit redundant, but since it is a separate paragraph, with no "Additionally..." or anything else linking these things, it must be about something else than the previous paragraph. I guess it's meant to prevent certain shenanigans, such as two wizards casting Find Familiar at the same time, with same components, for half the cost, or doing several Snare castings from a single rope (hemp rope is surprisingly heavy to carry around). Not really relevant for this QA.
So we are left with: You can use a component pouch or a spell casting focus in place of a material component, if it does not have a cost. Let's do so!
Components: V, S, M (a component pouch or a spell focus, which is consumed by the spell)
Looking through the rules, I can't find anything, would stop the spell from consuming the component. The pouch or the focus takes the components place in the casting of the spell, which requires it to be consumed.
If you use a component pouch or an arcane focus in place of a consumed material component, then the pouch/focus is also consumed in place of the material component.
It also makes narrative sense. Consider making a homunculus. The material of the homunculus needs to come from somewhere. You'd need the 9th level Wish to make it materialize out of thin air.