You are exaggerating the extent of progressive discontent with Obama.Obamas lows in Gallup was never as low as Biden,Trump,Reagan,Bush 2 etc.If he had lost that much progressive support he would have.If he had lost that much progressive support he would not have won a second term.
Biden's numbers tanked because of inflation issues that started after he was elected, Obama got elected during a financial crisis so people didn't blame him for the bad conditions.