[Guido]

Watched the 22nd episode, though it's the end for the TV series the conclusion has yet to be reached.

Surprises and revelations were unlocked heralding unexpected twists and a saddening truth.

Spoiler:

After all, wasn't it supposed that the Quartz being the impurity that triggered all this mess?

The issues returned back with the Scub Coral, which according to Ao's timeline they would end up consuming all of Earth.

However, the circumstances which led the Scub Coral to consume the Earth entirely in both Renton and Eureka's timeline were different, or that's what I want to believe.

And, just like Ao I simply couldn't make of Truth at the end. Implications twistedly suggest that Ao was forced to shoot the Quartz Gun, and thus rewriting the timeline again, and whether I want to believe if that in did happen then is uncertain if the timeline became worse or improved upon.
That's if Ao truly shooted the Quartz Gun.

Spoiler:

There's still some ground to approach and walk, because the story isn't finished and not with the seven pillars of Light calling to Renton and his Nirvash, time-jumping 10,000 years later to his timeline where the Scub Coral seemingly drained life from most of the Earth.