Consider [expr.call]/7:

The postfix-expression is sequenced before each expression in the expression-list and any default argument. [. . .]

The problem is that expression-list is defined as initializer-list, which contains initializer-clauses and not expressions. Maybe we should consider retiring expression-list as a grammar non-terminal to avoid confusion. It's been defined in terms of initializer-list since C++11.

Proposed resolution

Change [expr.call] paragraph 7 as follows:

The postfix-expression is sequenced before each expressioninitializer-clause in the expression-list and any default argument.

Alternatively, we can use regular font for "expression", like we do in many other places in the wording when expression-list is discussed.