Your installments follow a French amortization model, meaning:
each installment has the same total amount
the interest portion decreases over time
the principal portion increases over time.
➡️ How French amortization works
In a French amortization schedule:
1️⃣ Each installment has the same total amount.
2️⃣ The installment is composed of:
interest portion
principal portion
3️⃣ Over time:
the interest decreases
the principal increases
because interest is calculated on the remaining principal balance.