It’s pretty clearly abusive and not under the scope of AC privilege. In fact multiple cases have resulted in companies with similar behavior being forced to turn over the material.
You can only say that if you'd seen the contents of the communication.
This is like the legal version of encryption. Why would you hide all these conversations unless you have something to hide?
AC privilege is a critical part of the legal system, and so cannot be circumvented, so without an escape hatch for abuse, any company (or gov agency) could permanently shield everything they have from subpoenas, etc
Hence the rules for privilege set out that abuse of privilege can waive some or all privilege from your communication, even things that would otherwise be legitimately protected.
So blindly CC’ing counsel not only does not protect things that aren’t legitimate, but can remove protection from things that otherwise are.
The only way for an outside party to determine that is to see the contents of the communications. If an outside party can see the contents of your communications, they are not private.
The party claiming malfeasance does not need to show actual invalid content, it is enough to show a systemic behavior or pattern of misuse. The inability to see the content in that misuse is why, in general, abuse of privilege doesn’t void AC privilege on a few documents, but can completely negate all of it.
Competent businesses do not try to be clever, and include training that says not to try simply cc’ing counsel on everything. Because if you are cc’ing counsel on everything you are very clearly making a case that the content of the communication isn’t relevant to whether or not you are including counsel, and so you can lose privilege.
As I said elsewhere, this isn’t new or novel, and is a very well understood limit on AC privilege.