The worse results likely refers to results for advertisers but this will impact Meta’s ad revenue in the long run.
The article cited an example with almost zero sales with CPMs of $250, which is crazy high. I’d also bet the biggest chunk of advertisers using these tools don’t have sophisticated advertising strategies or resources. Many of them will probably pause these poor performing campaigns and be very restrictive with future budgets until performance improves.
In short, Meta took a lot of money in a short time but didn’t earn much money back for advertisers, so they will spend less in the future and less money make Meta sad.