Aluminum Design Manuals 2010 to 2015 Flextural Changes

[see_gen_notes]

I'm in the process of updating my calculations to comply with the 2015 manual, specifically referring to part 1, chapters F4.1 (2010) and chapter 2 for the yielding limit state. It appears that the flexural strength has increased from 1.3 to 1.5. I'm curious if anyone knows the reason behind this increase. While the enhanced capacity is beneficial for my purposes, I want to ensure that I haven't overlooked any relevant information. Any insights would be greatly appreciated.