Estimates on the lifespan of CD- and DVD-Rs vary wildly, from between two and 100 years. In 2004, the U.S. Library of Congress sponsored a study that estimated the shelf life of recordable discs available at that time. It simulated the aging of CD- and DVD-Rs stored in perfect environmental conditions (that is, a room temperature of 50 percent humidity with no sunlight, and no rough handling).

The study concluded that most recordable discs stored in ideal conditions would last at least 30 years, but the results varied wildly by brand. However, it also stated that “discs exposed to more severe conditions of temperature and humidity would be expected to experience a shorter life.”
https://www.howtogeek.com/682807/the-cds-you-burned-are-going-bad-heres-what-you-need-to-do/