https://www.economist.com/leaders/2020/09/19/the-ecbs-lack-of-credibility-could-hamstring-europes-recovery

"If the practical effect of budgetary loosening is to let the central bank take a breather, the chances are that the exchange rate will appreciate, offsetting some or all of the stimulus. The monetary taps must stay fully open for the extra fiscal stimulus to have the desired effect. That is what is happening in America."

Can you help me employ the Employing the Mundell-Fleming model with flexible exchange rates and perfect capital mobility to explain the first part of the sentence, providing economic intuition and a graphical analysis