Low-E window opening panel "hazing" up
&quot;Hazing&quot; within a dual-glazed window or door is a symptom of failure in the sealing that's supposed to maintain unchanged whatever (air, other gas, vacuum) is within the space between the two panes of glass.
Windows and sliding doors in my house were replaced with dual-glazed panels in 2008; several panels have recently developed a similar appearance. The manufacturer (Milgard) provided a lifetime warranty to the original purchaser, and Milgard's immediate reaction to my warranty claim was to schedule a date for replacement of the defective panels.