From what I understand it’s mostly TSMC and the memory providers being out of capacity over the next few years.
So it’s not even about datacenters.
Here’s a Reuters article about TSMC: https://www.reuters.com/world/asia-pacific/broadcom-flags-su...
So this is actual committed contracts with all kinds of companies such as Apple, NVidia, AMD.
Also, the whole reason they can’t build data centers faster is precisely because of this.