Proposed resolution (approved by CWG 2023-05-12):

Change in 7.6.2.7 [expr.unary.noexcept] paragraph 3 as follows:

If the operand is a prvalue, the temporary materialization conversion (7.3.5 [conv.rval]) is applied. The result of the noexcept operator is true unless the expression full-expression of the operand is potentially-throwing (14.5 [except.spec]).