Hi, I found this old post stating that world buffs are not layer specific: WoW Classic Hotfixes – Updated November 16 - WoW Classic / WoW Classic General Discussion - World of Warcraft Forums.
Is this also true, on the current anniversary realms?
I get buffs even when not on the “correct” layer, so confirmed.
To receive a buff you can be on any layer, but to pop a buff you need to be on the layer without a timer.