Ideas:

1. The left part of this glyph perhaps is the inverted sign between the 'sun' and the 'fish' in

May we assume that this link between 'sun' and 'moon-fish' represents the rays illuminating the moon? If so, then the inverted variant (as seen in the glyph above) perhaps is indicating that the rays of the sun now will come from the opposite direction.

2. And to me it looks as if there is a little moon on top of this inverted 'ray-sign'. South of the equator the Waning Moon will show as this little moon-sign, contrary to what we see on this side of the equator.

In my childhood I was taught that the Waxing Moon looks like this sign, the shape of a comma (,) a word which in the Swedish language sounds exactly like the word for 'come', both being 'komma'. The Waning Moon looks like a 'G', as in 'GO' (not needing any explanation because the Swedish word for 'go' also starts with G).