AI Max is on by default, and the default is not safe

Automation that flatters one campaign can quietly cost you across the account. Test it at campaign level before it goes anywhere near everything.

What actually changed

Google has expanded AI Max into Shopping and to a much wider set of advertisers. In independent testing, a large majority of advertisers saw neutral or negative outcomes once results were measured at account level rather than campaign level.

Why the reporting misleads

Automation is very good at finding the conversions that were going to happen anyway and claiming them. Look at the campaign it runs in and it often looks excellent. Look at the whole account and the incremental gain frequently disappears, because it cannibalised campaigns that were already working.

How to actually test it

One campaign, a holdout, and a fixed period. Judge it on total account revenue and total account cost, not on the campaign that has every incentive to look good. If it cannot beat the account level number, it does not get rolled out, however impressive its own dashboard is.

I check these against the original source before publishing, and I will send you the source if you want to see it. I do not quote a number I have not read myself.