@tiglet Welcome to Mayo Clinic Connect! Responses here by @cheyne and @windyshores are right on.

Unfortunately, many PCPs do not consider declining eGFR to be "a big deal" until it is a big deal. Foremost is figuring out what might be causing a decline, and we always want to look at a trend rather than a single test result. Are you hydrating enough? Are you getting over an infection? Are you taking antibiotics? Has there been a change in medications in any way [type/frequency]? Different labs processing your samples? Change in healthy diet protocols? All these can be factors that might change up our numbers.

Health conditions can contribute to declining eGFR. Uncontrolled diabetes or high blood pressure, side effects of medications [sometimes long term], lifestyle, or genetic factors can all play a part, too.

Yeah for you, already changing up your diet. Sodium, phosphorous, potassium, calcium, and processed foods are important to watch on your intake. Hydration is key, also! Have you felt any difference, feel better but cannot "quite" pinpoint why? Subtle changes can have a big impact!
Ginger