This has happened to me once and I can say it’s up there among a detailers worst nightmare.
In my case it also happened when I decided to reach for Bug Remover spray in order to help clean up the front bumper on this vehicle.
Sure it cleaned the grime off... And I went ahead and sprayed the entire front bumper while I was at it. I followed up with a good rinse with the hose and then a quik wipedown with rinseless wash and moved on to something else...
But when it came time for me to be almost done with the full detail and the car was in direct sun I noticed these crazy streaks on the front bumper and I immediately knew they could be a big problem.
Now the part I’ll never be completely certain about is when and what exactly caused them. I don’t recall seeing them in my pre inspection nor do I have close enough before pics to be able to see if they were already there.. But if I was at fault for causing them it would’ve either happened during the claying, because I doused the hood with D114 and of all times I diluted it with tap water + I was working at night and it’s possible I might’ve forgot to fully dry the front bumper...
The other cause could’ve been because of the Bug Remover Spray. That color is so hard to see even in the pictures and they weren’t noticeable until the car was in direct sunlight.
But I can report that absolutely nothing I tried could remove or bearly even minimize those chalky streaks because they seemed to be permanently etched into the bumper. I tried APC, degreaser, Magic Eraser, aggressive compound compounding, Megs Wheel Brightener, I tried everything!
Customer showed up to pick up the car and I was still busy with the finishing touches i.e. cleaning the windows.. And of all places he decided to stand directly in front of the car while he waited. I felt horrible. I’ll never know for certain whether they were on there before he brought me the car or if I really was at fault for causing them... It was a tough learning experience. Always do a thorough pre inspection, don’t just dive in until you do and take pics too.
...But as far as those streaks, I hate to sound negative but they I doubt you’ll be able to remove them. There was a similar question a few days ago with a guy who etched his gelcoat with degreaser or something.