Fluctuation of eGFR of > 10% in two months

Within two months I have seen a drop in my eGFR from 53% to 39.4%. It does have a history of fluctuations but this one seems extreme. I have blood pressure medication that I am taking (norvasc and chlorthalidone) and my pressure seems controlled (< 130/80), my A1C was 6.7 I was started on Ozempic 2 months ago and it has dropped to 6.4. So, I’m not understanding why the large drop.