Who are you supposed to lend your money to? Companies are saving more money, they ended up becoming net lenders. That's why inflation is low. Ironically, low inflation also makes the problem worse, because companies can save even more with low inflation. The threat of being forced to invest the money is gone. Ironically (yes I am repeating myself), low interest rates also increase the savings rate of companies because it is just a windfall profit for many of them. Consumers get loans with bad conditions so they don't borrow and even if they did, incomes are stagnating, so betting on a raise in the future may seem foolish.

The answer is to increase the total investment rate via infrastructure bills or to just inflate excess corporate savings away with stimulus checks. Inflation will allow the Fed to raise interest rates, which will cut into the corporate savings rate and after that point everything will return back to normal.