Few things retain their snow-white color over time.
However, this is not a reason to refuse them and throw them away immediately.
A few cheap products that your grandmother used will help you with this.

How to restore snow-whiteness to things
Regular baking soda will help make things snow-white again. A solution is prepared on the basis of the powder in the following proportions: 100 grams of soda and 500 grams or 1 kilogram of salt are taken per 5 liters of water.
The items should be kept in this solution for at least two hours, then they should be soaked in a soap solution overnight and rinsed in the morning.
The second method of bleaching at home is based on the use of half a bottle of hydrogen peroxide and a few tablespoons of baking soda, which must be diluted in warm water and soak the items there for 20 minutes.
If the stains are really serious, then the method with heavy artillery will suit you. Mix soda and vinegar in equal proportions, rub the stains with the mixture, leave for 15 minutes. All that remains is to wash the clothes.
Earlier we wrote about which 3-penny folk remedies will help with yellow stains on a pillow.