This answer from Mood Ring Producer

[chaotic93]

In a 2019 interview:

 

What are your thoughts on the song landing on the Japanese edition of Glory only?
Writing Mood Ring for Britney was never about where or how it would come out. Oddly, I never put too much thought into that. For me, it was always about when the song was coming out. From my understanding, Glory had started taking a more solidified shape after Britney had recorded Mood Ring in June 2015… We are living in a renaissance era for music where all artists and audiences are subject to the Internet. In an industry where Mike Posner’s “Pill in Ibiza” remix can become more popular than the original, or Katy Perry’s “Wide Awake” can be included in a complete confection repackage, then hit Top 40 at #1, why should anyone worry? If audiences attach to it, the song will find its way to the top of the pile, yet again. A hit is a hit be it released on a standard edition, Japan deluxe, or a repackage. I am blessed and thankful to have experienced a lifelong dream, come true.

[lustwecantcontrol]

Yeah in the digital age it doesn’t really matter as long as the song is actually released. If It was the year 2000 when Glory was released then Mood Ring would be lost so to speak.

 

Also it seems from what he said here and yesterday it most likely ended up as a bonus because they felt the later material was stronger since she recorded it so early on. 

[Roxxy]