Any clue what this is or how to remove? They have an odd iridescent look. Some globs, some spots. Commercial glass, not very well maintained.
Could be oil? Have you tried cleaning yet?
If you can’t scrape it off, then you can’t do anything about that. It’s on the inside (middle) of the glass. One time I got to do a residential job where all windows were foggy and dirty on the inside. One method I know how to fix this - new window.
