In servers such as Cubecraft and The Hive that require a resource pack to be applied when joining, if you are disconnected from the server by putting your device into sleep mode, the screen will become solid color, and you will need to restart Minecraft to fix it. This happens especially often on iOS/Android and Chromebook.
How to reproduce
Join a server that requires a resource pack to be applied when joining on those devices
Put your device into sleep mode and start Minecraft again
Expected result
Return to server list without such bug
Actual result
Do not return to server list
Screen becomes solid color
You will need to restart Minecraft to continue playing
Additional notes on how to reproduce
It says to sleep and restart Minecraft.
For more details
In that state, go to sleep → wake up