The Eyes of Night feature from the Twilight Domain Cleric, introduced in Tasha's Cauldron of Everything pg. 34, grants darkvision to the cleric:
You can see through the deepest gloom. You have darkvision out to a range of 300 feet.
It also allows the cleric to share this darkvision with willing creatures:
As an action, you can magically share the darkvision of this feature with willing creatures you can see within 10 feet of you, up to a number of creatures equal to your Wisdom modifier (minimum of one creature). The shared darkvision lasts for 1 hour. […]
It's clear that the creature needs to be within 10 feet of the cleric for him to use an action to share the darkvision. But once shared, does that creature needs to be within 10 feet of the cleric to be granted the benefits of the darkvision from Eyes of Night? Since the sharing has a duration 1 hour I'm wondering what if a creature that wandered far away from the cleric would still be granted this benefit.
Best Answer
The darkvision stays for its duration.
This works similarly to a spell's range and effects. For example, the spell darkvision has a range of touch and a duration of 8 hours, but this just means the target of the spell must be withing range when you give it the effect. The same logic applies to the Eyes of the Night feature: you can target a number of creatures you can see within 10 feet of you, and these benefits last for 1 hour.
If an effects needs you to stay close to its source or beacon, the game will tell you. This is the case of continuous area effects, such as auras, which specify that a creature gains certain benefits while withing that area / within that distance from the origin.
Another similar case is Mordenkainen's Faithful Hound, which specifies that the spell ends if you move more than a 100 feet away from the spectral hound.