Overcoming flour or other nonmagical ways to defeat invisibility

I am looking for ideas on how to defeat a flour trap. As a rogue, I rely on sneak attack to really damage my foes. The plan for taking on the BBEG is the party will make me invisible with our wand of Greater Invisibility. However, I know the enemy has set up several flour traps and uses telekinesis to disperse the flour into the air, making invisible creatures immediately visible.

However, flour is tricky. If you get it wet, it does not clean it off. Instead, it only makes it sticky. How could I overcome a flour trap and resume my invisibility? I think my DM is doing this because we have used flour against invisible creatures he’s sent after us, and I think he is hoping we come up with a clever way of defeating it so he can use that same thing in the future. So, I’m not entirely sure I want an answer, lol.

To make this question more specific, we have at our disposal a cleric, a wizard, and a fighter. The cleric can prepare Create Water, but that will not help. Prestidigitation only clears one cubic foot per round, so the greater invisibility will wear off before the flour is entirely cleared. Is there anything that can clean an entire five foot square in a single round?

How does Invisibility work if you cast it while observed?

In PF2, undetected and hidden are distinct conditions. A literal reading of the invisibility spell suggests that, upon casting the spell, the caster automatically becomes undetected.

Cloaked in illusion, the target becomes invisible. This makes it undetected to all creatures, though the creatures can attempt to find the target, making it hidden to them instead.

If the caster is undetected, then other creatures can attempt to find them by taking the seek action on their turns.

However, the rules for being invisible seem to contradict this:

If you become invisible while someone can already see you, you start out hidden to the observer (instead of undetected) until you successfully Sneak.

Suppose a spellcaster is being observed, and they cast invisibility. Do they become undetected, or do they become hidden?

If they want to become undetected, would they need to use an action to Sneak after turning invisible?

Greater Invisibility vs Swift Quiver

The scene: A level 10 College of Swords Bard (includes extra attack). Crossbow Expert. Sharpshooter. 20 Dexterity. Hand crossbow + 1.

Intelligence is his dump stat so he needs to ask a friend what to pick for his magical secret.

One is definitely Find Greater Steed, because he is going to ride on a griffon while raining down death with his hand crossbow. The other may or may not be Swift Quiver.

Greater Invisibility will give me 2 attacks with my action, 1 attack as a bonus action, +10 to hit with advantage.

Swift Quiver will give me 2 attacks with my action, 2 attacks with my bonus action, +10 to hit.

Ignoring opportunity costs, spell slots costs, defence and anything else other than crossbow damage per round, at what point is it better to use Swift Quiver vs Greater Invisibility?

Does activating a Tentacle Rod break the invisibility spell?

The Invisibility spell ends when the target attacks or casts a spell:

The spell ends for a target that attacks or casts a spell.

The "Tentacle Rod" magical items lets the user direct three tentacles to attack target(s):

While holding the rod, you can use an action to direct each tentacle to attack a creature you can see within 15 feet of you. Each tentacle makes a melee attack roll with a +9 bonus. On a hit, the tentacle deals 1d6 bludgeoning damage. If you hit a target with all three tentacles, it must make a DC 15 Constitution saving throw. On a failure, the creature’s speed is halved, it has disadvantage on Dexterity saving throws, and it can’t use reactions for 1 minute.

Does activating the Tentacle Rod break the invisibility spell? I’m not sure if "directing each tentacle to attack" counts as attacking yourself.