This is a sign of high or excessive humidity inside your home which will worsen in cold weather.
There are many ways to help lower humidity, turn on a dehumidifier or open windows frequently to let moist air out. You can also run exhaust fans more often.
If you can get humidity down to around 30 – 35%, windows will be clear of moisture on the inside.
Yes, vinyl siding has a fade warranty usually for a period of time and is measured by Hunter units. Not all manufacturers have the same fade warranty.
There are several thicknesses of vinyl siding, and some manufacturers use more additives to hold the colour longer.
The siding may be thin due to poor quality (thickness of siding) or a manufacturer’s defect. It may also be due to improper installation.