I went in to the Stage 3 CKD zone, from eGFR blood results and it was kept an eye on initially. I did see renal at one stage (after a while of my GFR going down and having the extra risk factor of Rheumatoid Arthritis) who checked a lot of things out and did a kidney ultrasound. I don't have high blood pressure or diabetes.
I was taking ibuprofen regularly as part of my pain relief medication, mainly for RA but I also have OA in my knees and other conditions. I was advised to stop the ibuprofen and my eGFR results went up a bit (in the right direction). It included NSAIDs generally, not just ibuprofen.
I have bloods done pretty regularly anyway, so easy to keep track of my GFR, and it's a bit of a balance. It's not that I can't take any ever again, but it's more when the balance outweighs, eg having it occasionally, or a shorter burst of taking it more often. So more if I'm, say, having a really bad flare, especially if I'm off my RA meds for some reason, like an infection. People react differently though. Time and monitoring helped in my case.