Even your link says there isn’t a rule and to be very explicit with your parentheses as to not confuse anyone. So instead of bringing up links that partially agree and then try to say your way is fact why not admit that its all in how you look at it, and that the question is very flawed in its mere existence.
I already said this on page one, and further repeated i think it should be a rule but isn’t! Some calculators put implied multiplication(ie 2(3+1), 2x etc.) aka juxtaposition ahead of explicit multiplication(ie 2*(9+1), not because it is a rule, but rather because it is the way many people naturally mean to write the equation. It is merely an assumption and like many say should and would never be used in any actual math application.