An interesting combo came up in gameplay: An invisible party member chose to defend another party member using their non-spell, non-attack reaction (arrow catching shield.)
In the description for the invisibility spell (PH pg. 254), it says:
The spell ends for a target that attacks or casts a spell.
In the description for the arrow-catching shield, it says
In addition, whenever an attacker makes a ranged attack against a target within 5 feet of you, you can use your reaction to become the target of the attack instead.
According to the rules of the invisible condition (PHB, pg. 291):
Attack rolls against you have disadvantage.
Should the attack now be with disadvantage, even though it's already been made?
The central question is Does redirecting an attack to a different target cause the attack to be made under the rules for the conditions affecting the new target?