Why has my lease/rental interest rate/monthly payment suddenly changed/increased?

The size of the monthly payment depends on several factors, one of which is the variable part of the interest rate of the loan, i.e. EURIBOR. EURIBOR is an index (rate) set by the European Money Market Institute (EMMI) at which banks borrow funds in the interbank market of European Union countries. Since 2015, the EURIBOR rate has been negative, but in view of rising inflation, the European Central Bank (ECB) decided to raise the base interest rates. As the EURIBOR rate rises, so does the monthly payment. The amount of the payment can be changed every 3 or 6 months - depending on what part of the variable interest is specified in your contract.