Battery change not yet necessary ?

Hello guys, I need your expert advice. I had my Dacia Sandero 1.2 16V (built in 2010) changed to ATU ÖL and brake fluid. They then called me and told me my battery only had a power of 79% and I should have them changed right away, they would recommend the change. Since I have no idea of cars at all, I simply agreed to it. The car started but still normal and I had not had any I had a 640A and 60Ah battery in it before. The test showed the following: voltage 12 96V starting power 79% 640A EN <0°C charging condition 100% Now they didn't have the same battery size as promised, but one with 54AH 530A. My father thinks the battery would have been enough for the Dacia. What do you think? And should I not require the installation of an equally large battery at ATU, how ve Is the power of the battery not worse? Thank you for your advice and greetings Lauri