There’s always a trade-off
By now everyone should be aware of the drama in the US surrounding Silicon Valley Bank (SVB), Signature Bank, and many other unnamed banks that a “senior Treasury official” said might have similar issues.
Essentially these banks attracted a lot of deposits by offering favourable conditions and then used the cash to buy long-dated government bonds, making a silly, unhedged bet that rates would stay low and they could profit on the interest differential.