Many complaints here about degraded DVDs. So I made a test. Took a DVD of the cheapest kind - I would not recommend this brand… I burned something on it to make it full and then I put it for about five months into a with water filled plastic box.
After five months I took it out and it looked terrible. The shiny side was a bit white with many strains and not shiny anymore. I put it into the player and it did not even start to read it. To me it was clear - that was to much for the DVD. But I forgot to throw it away. After one ore two days I looked at the DVD and the data side was shiny again. I put it into the player - and it played without any problems. I checked the quality of the disk. It looked okay. Sadly I deleted the reference data of this disk when it did not work at the beginning. But a not watered disk of this brand shows similiar test data.
After now more then another five months I still have the DVD - and it looks like new. So moisture cannot be THAT problem.
Perhaps next I will start with a heat and UV test