• Surely that would mean the answer’s ambiguous, no?

    No. Exponents before Subtraction. Order of operations rules.

    The lack of brackets means we can’t know definitively if - is included or not

    The lack of brackets mean we definitively do know that it’s not included, because to be included, it would have to be in brackets.

    I’d argue that -3 represents negative three, not subtract three

    It’s actually 0-3. There’s an unwritten 0, just like if the first number was positive there’s an unwritten +. 9 is actually 0+9. All operations on the number line start from 0.

    negative three is it’s own distinct number from positive three

    “positive 3” is actually 0+3.