[basic.scope.block] p1 The note should be as a normative rule

Each

• selection or iteration statement ([stmt.select], [stmt.iter]),
• substatement of such a statement,
• handler ([except.pre]), or
• compound statement ([stmt.block]) that is not the compound-statement of a handler

introduces a block scope that includes that statement or handler.

[Note 1: A substatement that is also a block has only one scope. — end note]

Isn't that note should be phrased as a normative rule? My proposal is that

Each

• [...]
• substatement of such a statement that is not a compound-statement,
• [...]
• compound statement ([stmt.block]) that is not the compound-statement of a handler

introduces a block scope that includes that statement or handler.

[Note 1: A substatement that is also a block has only one scope. — end note].

if(true) {
}

The substatement is a compound-statement, hence the second bullet does not apply but the last bullet does, which means the substatement only introduced one block scope.

Start by reviewing the quoted [basic.scope.block] wording and the proposed change to the substatement bullet. Check how the example if(true) {} is covered by each bullet and whether the wording states the intended single-scope rule normatively. Done means the adopted wording is precise and consistent with the surrounding standard text.