Straightforward issue here: in the D&D 5e version of true polymorph, the creature or object becomes permanently polymorphed into the creature or object of the caster’s choice after an hour has passed. Down the line, if a caster used the detect magic spell and examined the newly transformed creature or object, would they be able to detect magic?
In other words, if a wizard transformed an adventurer into a spoon with true polymorph, waited 61 minutes and tossed the spoon into a drawer full of perfectly normal spoons, would one of the party members then be able to use detect magic to determine which of these spoons is their party member?