Inconsistency with the 夕 component between regions and with Kozuka Gothic

[NightFurySL2001]

With reference to Kozuka Gothic Pro on Adobe Fonts, there seem to be a design change when developing Source Han Sans (JP): most characters (with the exception of 夕 itself) with 夕 is changed from an opened form (touching the bottom only) to a closed form (touching both top and bottom).

夕 for JP (also KR and CN) is mapped to CID+14039 with the name uni5915-JP that has only the bottom touching, while 夕 with both top and bottom touching is at CID+14040 at uni5915-TW, which only maps to TW and HK. However, in other cases, the JP glyph is the one that has both top and bottom touching (e.g. 歹 CID+22656 uni6B79-JP) and mapped to KR/TW/HK, and the CN glyph is the only one region that has only the bottom touching (CID+22657 uni6B79-CN).

Also noted in #326, this component is unnecessarily different between regions.

Questions:

1. Why did such a change from Kozuka Gothic to Source Han Sans take place? Is there any consideration behind this change?
2. Is there any plan to unify all 夕 forms? If so, which form will be used (opened or closed)?