Remove rust stains from concrete patio slabs

We have beige concrete stones that are supposedly coated or impregnated. That’s why you’re not supposed to use a pressure washer on them. The rain initially washed away some stains, but not everything. For example, we once foolishly stored oak wood briefly on the terrace. The tannic acid left its marks, which we managed to reduce but never fully got rid of. I also once got rust stains when I placed the children's gates on the terrace during lawn mowing. Unfortunately, water had collected in the pipes and then flowed onto the terrace. If I remember correctly, we also used rust remover. Since we have a roof now, the effect of the stone coating has completely disappeared. For the first few years, I tried with a garden hose and broom, struggled with it, and was still not happy. Now I use a pressure washer with a circular surface cleaner once a year and am very satisfied. The terrace almost looks like new then. For the grease splatters/drips from the grill, we regularly use Bref Power. That works pretty well.

We have the completely standard gray concrete stones (are not impregnated at least you don’t notice anything)

The problem with the Kärcher is it washes out the joints again

Does anyone know a cleaning agent that we can work in with a brush and rinse off with the garden hose that can remove as many stains as possible?

The problem with the Kärcher is that it flushes the joints clean again

That is the disadvantage. But that also happens with the garden hose. On the terrace, I accept that, Kärcher with the surface cleaner once over and then sweep in new sand. Then the joints look nice again.

The driveway could also use a treatment after more than 10 years, but we have eco-pavers there with wide joints which are filled with small gravel. If all the little stones are washed out with moss, soil, and plant debris, you can’t sweep them back in and have to redo it completely.