How can I treat foggy double pane windows so they’re not so ugly?

maybe this video will help...

Window film! Check this out!

https://www.decorativefilm.com/static-cling-films

https://windowfilmworld.com/collections/privacy-window-film

http://www.wallpaperforwindows.com/m/viewcategories.asp

This will disguise it, still look tasteful and let light through.

You might try this BUT you will lose the insulating factor.

https://www.doityourself.com/stry/defogging-a-double-pane-window

When the windows fog up like this, it means the vacuum seal has broken. The best thing to do is replace the window. I know that's expensive, but perhaps you could find some in a salvage yard. Habitat for Humanity also has stores where you can purchase odds and ends of things they haven't used when building a house.

There are companies that have a way to evacuate the moisture then insert a valve in the glass

The seal between the glass panes has failed. The inert gas, usually Argon, has leaked out and replaced with air. The glass panels will need to be replaced not the whole window. Ace Hardware sells double glass panels and they also install. The niche market for repairing, as in the video, cleans the glass but doesn't address the broken seal or energy efficiency of the glass.

The seal has a leak in it somewhere, so the glass needs replacing and not the whole window.

Check around Angi's list for professional window contractors in your area, they can replace the glass only.

Yes, Hometalk has a great guide on this here: https://www.hometalk.com/diy/clean/windows/how-to-clean-cloudy-glass-windows-44456953

Be aware that window film will show people the inside of your house at night so keep drapes drawn at night time.

They won't clean if the seal is broken. Hang sheers or lace panels over them.