Qin Huai watched Zhao Cheng'an make snacks in the Li Mansion's kitchen for over an hour, pretty much figuring out the current situation.
This point in time is now a full six years since last time. Xia Sheng is already 13 years old, if you count actual years, so it's no wonder he looks like a teenager. People have readily accepted the fact that Zhao Cheng'an's appearance hasn't changed a bit in six years; originally, Zhao Cheng'an looked like a boy of 12 or 13, very fit, a style many adults in this era struggle to attain their whole lives.
Plus, everyone just assumed Zhao Cheng'an had a problem with his brain and was a fool, so any difference in appearance compared to normal people didn't seem odd.
Not to mention, from a spirit crossing-the-tribulations point of view, being a fool is quite convenient; as long as you're a fool, every strange behavior is reasonable.
