Ah, interesting! I was doing it as a math input. And also completely missed the 2(2+2) being different than 2*(2+2) when testing with Gemini and GPT. Interesting!
I explain that in my original post above: it's kind of a cheap shot ambiguity trap TBH.
Discussion
Folks (understandably but erroneously) assume the short hand notation implies parenthesis around the second half of the equation, changing order odboperations.
You fell into the trap, like 75-85% of people.
And I'd be willing to bet 90% of the people that guess 16 are getting it right accidentally but can't articulate why others guess 1.