Does the Grung's racial-trait poison work on all bolts when using a crossbow?

Question

With the Grung's racial trait Poisonous Skin, you can apply poison to your weapon as part an an attack:

You can also apply this poison to any piercing weapon as part of an attack with that weapon, though when you hit the poison reacts differently. The target must succeed on a DC 12 Constitution saving throw or take 2d4 poison damage.

Since crossbows are piecing weapons you could apply the poison to your Hand Crossbow. With the Crossbow Expert feat, you can attack again as a bonus action after attacking with a one-handed weapon, thus attacking 2 times in a turn with the Hand Crossbow. Same goes for the Extra Attack feature of a higher-level fighter with crossbows.

I am confused about the rules/phrasing of Poisonous Skin. In the One Grung Above sourcebook, "attack" is written in lower-case for this trait but has a cross-reference to the Attack action which is usually written in upper-case. I can see different scenarios how this works together:

1. You apply the poison to your piercing weapon (crossbow) as part of the attack and the poison counts for every bolt you fire with this weapon
2. You apply the poison to your bolt as part of the attack and can apply it again for the second bolt you fire with your bonus action, since the bonus action is an attack (lower-case) too
3. The poison only works for the first attack and can't be applied until your next Attack action (upper-case)

Question:

Does the Grung's racial feat poison work on all bolts when using a crossbow, whether you apply it on your crossbow or each individual bolt during your turn or does it only work for the first bolt you release and the poison can't be applied again until your next Attack Action (upper case)?

Answer 1

Yes, you can use Grung poison on each crossbow bolt

Despite the hyperlink from the word “attack” to the Attack action (which has since been removed), the One Grung Above sourcebook isn’t specifically referencing that action. The Attack action is different to “making an attack”, as detailed in Chapter 9: Combat of the Basic Rules and Player’s Handbook. In a nutshell (and to reuse part of another recent answer):

• Making an attack means choosing a target, making an attack roll, and if you hit, making a damage roll and dealing damage.
• Taking the Attack action is an action available to all characters that allows them to make an attack in combat. There are other ways to make an attack, including opportunity attacks, specific class features, casting certain spells (e.g. booming blade) and most relevant to this case, the bonus action second attack allowed when two-weapon fighting or via taking the Crossbow Expert feat.

As you note, the Poisonous Skin trait says:

You can also apply this poison to any piercing weapon as part of an attack with that weapon

This is the same kind of language used for the ammunition property possessed by ranged weapons like bows, crossbows and slings, as explained in Chapter 5: Equipment of the Basic rules and Player’s Handbook:

Drawing the ammunition from a quiver, case, or other container is part of the attack

So any time you are making an attack with a piercing weapon - regardless of whether you are using the Attack action or making an attack via other means - you can apply your Grung poison to your weapon.