Upgrade
From SWU Holocron
Rulings for Upgrade
Q: Can I play an upgrade card on an enemy unit?
Examples: Upgrade
A: Yes, upgrades can be played on any appropriate target.
Source: https://www.youtube.com/live/Msezhwc2WE4?t=1787
Q: Can Token Upgrades (Shield and Experience) be removed by "Defeat an Upgrade" effect?
Examples: Shield, Experience, Disabling Fang Fighter, Aggression, Other Rules, Token Upgrade
A: Correct. Experience and Shields are both upgrades (as noted on the top of the card and by the templating) and can be interacted with by any card ability that specifically references upgrades.
Source: https://garbagerollers.com/2023/11/08/rules-recap/