IIRC we try to avoid triply-nested lists. I suppose we could outdent 7.2.3 to 7.3 by conjoining the requirement from 7.2, and then split into sub-bullets case-wise:

(7.2) — For the overloads in namespace std:
(7.2.1) — The comparison function shall be an equivalence relation.
(7.2.2) — The expression *result = *first shall be valid.
(7.2.3) — [Note: For the overloads with an ExecutionPolicy, there may be a performance cost if the value type of ForwardIterator1 does not meet both the Cpp17CopyConstructible and Cpp17CopyAssignable requirements. —end note]
(7.3) — Additionally, for the overloads in namespace std with no ExecutionPolicy, let T be the value type of InputIterator.
(7.3.1) — If InputIterator meets the Cpp17ForwardIterator requirements, then there are no additional requirements for T.
(7.3.2) — Otherwise, if OutputIterator meets the Cpp17ForwardIterator requirements and its value type is the same as T, then T shall meet the Cpp17CopyAssignable requirements.
[...]
(7.3.3) — Otherwise, T shall meet both the Cpp17CopyConstructible and Cpp17CopyAssignable requirements.

Note that I've left the note - which pertains to the overloads in std with an ExecutionPolicy - in 7.2.3 instead of keeping it hidden at the end of a bunch of specification for the non-ExecutionPolicy overloads.

I'll prepare a PR with this reformulation if this comment gets more 👍 than 👎.

I think this wording has already changed now to fold the nested list into a single paragraph. This should be fine now, but please reopen if it's still not as good as it should be, @CaseyCarter.