The story is simple:

Google communication culture started as open and relaxed so people could go on a public internal forum and say their opinion "I think if we add x, y, z feature we can kill the competition". This is nothing specific to Google, it happens perhaps everywhere but Google wasn't policing it in written communication.

Then all these written opinions were gobbled up by lawyers during the discovery phase of endless lawsuits Google has to defend. It created constant headache so they said, we'll auto delete chats older than a few days unless you opt-out.

Now a court and this article say they are destroying evidence.

I've personally lost my trust in both the media and the legal system honestly. The incentives are just not aligned with good outcomes. The incentive for the media is more and more drama and the incentives for lawyers is always adversarial depending on who they represent.