Two related prompts, different results: Qwen 3.5 and Gemma 4 need different prompting than Qwen 3.6

With every new model release there's the "better than Opus 6.13" guys vs the "this is so bad, why did they even release it" camp and I'm always wondering which one is using it wrong. So I did a little test with 2 related prompts, 3 models and ran each combination 10 times. Short prompt: Mike grew up as one of 6 siblings and has 3 sisters. He has $25 and bought 5 boxes of apples for his organic apples business. To him, his siblings also gifted some apples, with each of his brothers giving him 4 boxes and his sisters 2 boxes each.