What would happen if you cast true polymorph in a creature affected by the Enlarge/Reduce spell?

Question

Partially inspired by this answer, what size of an object could you create with True Polymorph if the target was affected by Enlarge/Reduce? And what size would the object be after Enlarge/Reduce wears off?

True Polymorph says (among other things) (emphasis mine):

Creature into Object. If you turn a creature into an object, it transforms along with whatever it is wearing and carrying into that form, as long as the object's size is no larger than the creature's size. The creature's statistics become those of the object, and the creature has no memory of time spent in this form, after the spell ends and it returns to its normal form.

Enlarge/Reduce says:

Enlarge. The target's size doubles in all dimensions, and its weight is multiplied by eight. This growth increases its size by one category-- from Medium to Large, for example. [...]

Reduce. The target's size is halved in all dimensions, and its weight is reduced to one-eighth of normal. This reduction decreases its size by one category--from Medium to Small, for example. [...]

The two spells both require concentration so they would of course have to be cast by two different people. The options I see here are

1. Medium creature is enlarged to a Large creature and then polymorphed into a Large object. Spell wears off and the Large object is now Medium object since it's still a valid target for E/R.

2. Medium creature is enlarged to a Large creature and then polymorphed into a Large object. Spell wears off and the Large object is still a Large object as it's no longer the original target of the spell since it targeted a creature in this instance.

3. Medium creature is enlarged to a Large creature and then polymorphed into a Medium object since the creature is normally Medium. E/R ends.

4. Some option I haven't thought of.

Answer 1

Enlarge does increase the size of object you can turn the creature into, and large it will remain.

tl;dr the effect of true polymorph is to turn the target into a large object. That effect is still ongoing after the effect of enlarge ends.

1. The effect of enlarge makes the creature valid for turning into a large object.

2. True polymorph "transform the creature into ... a nonmagical object. The spell lasts for the duration"

3. When true polymorph is cast, it abides by the rules of the effect "object's size is no larger than the creature's size." and the effect is to turn the creature into a large object.

4. After true polymorph comes into effect, there is no more creature. "The creature's statistics become those of the object" so reasoning about the creature's size becomes moot.

5. The target of enlarge is still valid, so it's still under the effect of enlarge.

6. When enlarge wears off, the target would return to it's normal size, except for the issue that it's still under the effect of true polymorph.

7. Still being under the effect of true polymorph means it is the object that true polymorph turned it into, and that is a large object.