When you pause the game, everything seems stopped, but it isnt. When you unpause all the things that happened while you were paused will quickly happen. Easy ways to reproduce is to place a bucket of water, pause, then unpause after a while.
Linked issues
Comments
i can confirm this, fresh started the game,decided to kill a 'harmless' zombie but had to go afk iRL(pressed Esc to pause), came back to game, dead automatically cause the game did not paused, just the screen
Can confirm paused game looking at the sky at night came back unpaused and it was daytime
Can confirm. Applies to redstones too (tested with a repeater chain)