Attunement is a huge balance equalizer in 5e...honestly surprised the designers allowed this.
Funny thing you can do: infuse an item, have your high-Charisma Deception-proficient friend sell it to a shop keeper or other buyer, then walk away. Shop Keeper can Identify it via normal means (spell or short rest), and see that it appears to be a normal item. Then, infuse an item over your Infused Item limit, expiring the oldest infusion you just sold, leaving the buyer with a mundane item.
I've heard Crawford state the 3-item limit was more for user-friendliness than balance, and three was a fairly arbitrary number to set it at.
One of things about Eberron is that very few things that a regular PC can do that are not fairly well known. People in Eberron live in a world where Artificers are well known (especially to anyone who trades in magical items) and there will no doubt be several counter-measures developed to tell a fraudulent temporarily infused item from the real thing (as many real-world stores do now with counterfeit bills).
This is the setting that very explicitly states that people know Changelings exist and so act accordingly when the situation warrants it.
True, but is this explicitly stated in the the new book somewhere? Sure, a DM can hand waive it as being impossible (a DM can hand waive anything after all), but not mentioning it seems like a miss to me.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.