Being idle too long is not a bug on Minecraft Realms. It is done to prevent players from AFK'ing too long due to the cost of running servers. Although I do believe reading or writing a book being considered AFK is a bug.
I agree that this is an issue that needs to be fixed, but I quite like it. It makes the moss look overgrown and is sprouting life. But of course this needs to be fixed.
Being idle too long is not a bug on Minecraft Realms. It is done to prevent players from AFK'ing too long due to the cost of running servers. Although I do believe reading or writing a book being considered AFK is a bug.