The pandemic. This along with short supply do to broken supply chains is what caused the high inflation under Biden.
You are damned if you do and damned if you don't. Either pay high prices and have money to do so, or have no money to buy anything. I believe giving the stimulus was the right thing to do even though it created high inflation.
Because the alternative was:
The consensus among economic experts is if The economy wasn't stimulated, we would have went into a deep recession, Sharp decline of GDP, Much higher unemployment rate, longer economic recovery, and greater hardship and poverty.
Biden did an excellent job of keeping us out of a recession.