An increase in private savings always leads to lower interest rates because it increases the supply of loanable funds.

When people save more money, they have more funds available to lend to others. This increase in savings raises the total amount of money that banks and financial institutions can use to give out loans. Because there is more money available for loans, banks can lower the interest rates they charge borrowers. For example, if a lot of people decide to save their money in a bank, the bank might lower the interest rate on loans to attract more borrowers, since they have plenty of money to lend. So, when private savings go up, it often leads to lower interest rates due to the larger supply of money available for loans.