Bank bond portfolios are filled with low interest bonds from a few years ago. They are stuck with them and are unable to pay more yield given how their bonds are positioned. Its a death spiral.

This is a big part of the story - many banks can't pay more than 0.5% interest because the money from their deposits are locked up in low interest loans from the past. Their overall portfolio may average 2% given that they had to sell recent bonds to fund outflows to money markets. Basically, bank holdings have dwindled to the assets with shit yield and they are trying, and failing, to pass that shit yield to grandma's savings account. Grandma aint having it so they sell more assets. Spiral ensues.