The ECB dropped a requirement that collateral for lending is traded on a regulated market, with the exception of covered bonds. Should be easy to dump bonds on the ECB if you can value them however you like.
At the same time, the maximum amount banks can use of their own debt lowered to 5% from 10%.
Without looking at the collateral it’s hard to say anything underhanded is going on but making changes at a time like this looks suspicious to the market.