Weird automatically generated names

After @tchajed's !479 (merged) the following happens:

Lemma foo {PROP : bi} : ⊢@{PROP} ∃ _ : True, ⌜ 0 = 0 ⌝.
Proof. by iExists I. Qed.

Lemma bar {PROP : bi} : ⊢@{PROP} True.
Proof. iDestruct foo as (?) "?".

This names the automatically generated hypothesis x.

1 subgoal
PROP : bi
x : True
______________________________________(1/1)
_ : ⌜0 = 0⌝
--------------------------------------□
True

I don't understand where the name x comes from, but it's very annoying. The ∃ _ : ..., ... pattern is often used for inG, and the inG being called x is very annoying. It prevents one from using x for other variables.

Obviously, in this case I could use iDestruct foo as (name_for_my_inG) "?", but I really don't want to name that hypothesis.