I asked mine to turn on a light at 4.20pm everyday and it misheard me and chose 4.20am for all lights including bedrooms - not cool!
This link explains the issue:
The solution (workaround!) - create a new "Home" in your Google home app. Call it something different and move all your devices to it one by one. Invite your family members to it and delete the older Home. Then you can rename the home to the name your original "home" was called.
Sadly there is no way to stop this happening again! My advice is to use the devices own primary apps to create schedules. They're generally fuller featured too as Google home only supports the more basic primary functions.
