I was told it could be from glue/adhesive from the plastic the car is wrapped in.
P21s to the rescue. I love this stuff for jobs like this. Works so well on pretty much anything and it’s non abrasive. P21s completely removed them and restored the glass to new.
After:
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P21s to the rescue. I love this stuff for jobs like this. Works so well on pretty much anything and it’s non abrasive. P21s completely removed them and restored the glass to new.

After:

Sent from my iPhone using Tapatalk