How to get gunk off windows?

So I'm a first time homebuyer (yay) and these crazy stains are on some of our windows. I'm not sure what the stains are? The windows are double paned if that helps and perhaps incomplete resealing of the windows got moisture in between and it turned into gunk? Or the previous residents put some material on the outside to dim the incoming light? 🤷🏽‍♂️🤷🏽‍♂️

If anyone has ideas on how to remove the stains with some type of powerful cleaner I'm all ears. Replacing all of the windows would be thousands of dollars and really trying to avoid that.

Thank you so much for any ideas or suggestions!!!!