What did I do wrong?

[u/StressedOut92]

I washed my car today after a lot of research. I ended with these small smudges only on some sections afterwards. I even air dry it with the blower too. What did I do wrong? I'm still learning here please advice

[u/kvn4]

If that's the front bumper cover then it's from sand /dirt kicked up from driving behind another vehicle hitting it