Double Glazing Marks
They do have vertical blinds but I don't think it has anything to do with the glass.
You also have swirl marks at the bottom of the window.I t might be a combination of uncleaned glass before the glazing was sealed and/or a failed seal.
Do you see any water droplets or just the fog?
Do you know the window manufacturer? The failed glazing might be covered, you just need to find out who made it to access the warranty details.
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
B. Franklin 1759