Google's rationale for this is darkly hilarious: if the public is allowed to know what's happening in its trial, this will be converted into "clickbait," which is to say, "The public is interested in this case, and if they are informed of the evidence against us, that information will be spread widely because it is so interesting":

https://www.bigtechontrial.com/p/secrecy-is-systemic

Thankfully, this secrecy is struggling to survive the public outrage it prompted.

13/