[RPG] Are material spell components consumed during casting or during preparation

The components are only consumed when specified.

Player's Handbook p. 203 (or here in the basic rules):

Casting some spells requires particular objects, specified in parentheses in the component entry. A character can use a component pouch or a spellcasting focus 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.

No they do not require components at all including somatic or verbal for that matter. So casting an Arcane Lock from a Staff of the Magi doesn't require the 25g worth of gold dust nor would the Staff of the Woodlands require it for Awaken. It may seem "overpowered" but the typical druid doesn't go around making sentient armies of animals for good reason.

DMG p141 the section on magical items and casting spells from them.

The spell is cast at the lowest possible spell level, doesn't expend any of the user's spell slots, and requires no components, unless the item's description says otherwise.