It's a really really really short article. Really short. Please.
It gets to the point in the second paragraph: the green bubbles have bad contrast. It mentions the design of the green bubbles rank as "very poor" by accessibility standards.
I get it. It should be noted that enabling the Increase Contrast accessibility option in iOS/iPadOS does correct the issue to an acceptable level. Whether that should be necessary is up for debate.
It gets to the point in the second paragraph: the green bubbles have bad contrast. It mentions the design of the green bubbles rank as "very poor" by accessibility standards.
That's why it matters.