How to reproduce

1.  Load in a Minecraft world in your phone.
2. Go to the home screen and make a phone call or lock your device.
3. Re-enter Minecraft.
4. Do this couple more times if the textures are still fine.
5. Re-enter Minecraft.
6. Eventually the textures will bug out, causing weird and random textures.

This bug is fairly uncommon but will happen.

When this happens:

• All sides of sand have sandstone texture.
• Top side of grass is green gravel texture.
• Gravel is now light blue candle. Empty parts are filled with white.
• Staight rails are now curved, curved rails look like flat raw copper blocks, etc.
• Moss is now mud.
• Redstone dust block and item texture is broken.
• A lot of block and item textures have changed, this even include blocks and items in addon packs.