Hello Anet

One thing that comes to my mind is diet, Meat diet contains "non soluble" protein which can harm the kidney filters (nephrons)

So when my GFR was around mid 20s we switched bulk of our diet to to Lentil / Vege. and occasional fish, Lentil and vegetables have "soluble protein" and have benign impact on kidneys.

With this approach, I got approx 6 years of time span before the kidney transplant.

Best