Most cars are going to thinner oils I can't imagine why Hyundai would start suggesting 5W-40.
According to the manual: "For better fuel economy it is recommended to use the engine oil of viscosity grade 5W-30 (ACEA A5 or above). However, if the engine oil is not available in your country select the proper engine oil using the engine oil viscosity chart."
In case the chart is not visible, it shows 5W-30 and 5W-40 covering the same temperature range.
I think the TSB that most people reference is from a 2016 TSB. It isn't specifically a TSB for our cars because like Exeno wrote, 5W-40 is in the owners manual. Most aftermarket tuners recommend you use 5W-40 for better engine protection.