Can anyone explain why anybody would buy treasury bonds if HYSA gives more than that and guaranteed not going down in value?

Subject. My advisor or rather JPMorgan automated portfolio bought a bunch of treasuries and bonds, while the equities consisted only 10% of the portfolio. Can anyone explain why would anyone do that instead of just putting the money you want to grow at a stable but low rate into HYSA? I literally can’t think of a reason. They go down with stocks sometimes, and the yield is like 1-2%. It’s not even compensating for inflation. What’s the point?