Proposed resolution (approved by CWG 2023-01-06):
Remove 7.5.8.5 [expr.prim.req.nested] paragraph 2, including its example:
A local parameter shall only appear as an unevaluated operand (7.2.3 [expr.context]) within the constraint-expression. [Example 2:template<typename T> concept C = requires (T a) { requires sizeof(a) == 4; // OK requires a == 0; // error: evaluation of a constraint variable };