This bug has been affecting me a lot of times in my one year survival world. Once, twice, or even thrice a month, one or more of my banners displayed in my world have been getting corrupted or have been loosing it's color. This has been affecting me a lot since I sometimes have to get a lot resources to remake new banners.

Expected result: 

The banners will stay at it's normal state.

Actual result: 

Random banner/s in a world get corrupted for no reason.

 How to reproduce:

1. Entering the nether and going back to the overworld.
2. Not playing my world for quite a time.
3. Randomly happens.