In which case has the U.S. dollar weakened?

The U.S. dollar has weakened in various instances, notably against major currencies like the euro and yen during periods of economic uncertainty or shifts in monetary policy. For example, the dollar experienced depreciation in 2021 and 2022 as the Federal Reserve's low-interest rates and significant stimulus measures contrasted with tightening monetary policies in other countries. Additionally, geopolitical tensions and inflation concerns can also contribute to a weakening dollar.