Interesting that they think they're out of internal projects and acquisitions to (profitably) spend money on. Even more interesting that the stock seems to agree -- I guess investors already believed that growth is over, and are seeing this recognition of that as an alignment between reality and internal strategy.
The only major investment left would be computing infrastructures, but it's severely limited by supply. Even if Google wants to spend more money, simply there's no chips to buy. I don't see any significant future investment opportunities other than Waymo in the foreseeable future, but it seems still far from scaling out.
This strongly suggests that there's an opportunity to spend money relaxing this shortage. If your business growth is being throttled by suppliers, then investment either allows you to grow those suppliers, or vertically integrate them out of the picture.