In 2021 they should have known:

1. Long dated treasuries would almost certainly underperform long term if there were any interest rate increases

2. Interest rate increases were likely due to high inflation, low unemployment

3. Interest rate increases would correlate with a reduction in deposits

I’m not blaming a single person at all, but the bank in general should have been aware of this. While this seems more obvious in retrospect, it should at the very least have become obvious once the first rate hikes were announced