The following items should have the c:storage_blocks and c:storage_blocks/{material} item and block tags added:

Allium Petal Block: c:storage_blocks/allium
Pink Allium Petal Block: c:storage_blocks/pink_allium
White Allium Petal Block: c:storage_blocks/white_allium
Rose Petal Block: c:storage_blocks/rose

I can add the tags, but
Allium Petal Block: c:storage_blocks/allium
Pink Allium Petal Block: c:storage_blocks/pink_allium
White Allium Petal Block: c:storage_blocks/white_allium
Rose Petal Block: c:storage_blocks/rose

would all use the biomeswevegone namespace and not c since they aren't "common" tags they are ours, then all of them would be added to c:storage_blocks

Mods that add specific storage blocks, ingots, etc, still use the c namespace if they can be put as a / after the common tag, like c:storage_blocks/allium

What other mods?

Just to name a few; Mekanism, AllTheOres, Allthemodium, PneumaticCraft, Ars Nouveau, Actually Additions, Advent of Ascension, The Undergarden, Twilight Forest, Croptopia and Applied Energistics 2. Most mods that can add them, do.

I see what you are saying I looked at the undergarden, I'm gonna consult some other devs to see what the decision is here as it doesn't make sense to me to use the common id

If another mod adds a storage block for alliums, it's easier to unify them if they already have the same tag.

That only makes sense in the case of MC blocks for blocks that we add it doesn't make sense

Any update on at least adding the allium block tag? Have you looked at examples in other mods?

I moved them to c all of them