The Twilight domain has a channel divinity called Twilight Sanctuary. Among other benefits, it also has the following wording:
The sphere is centered on you, has a 30-foot radius, and is filled with dim light.
Can this actually darken the area if its already in bright light?
The wording "Is filled with dim light" is significantly different than most light sources which specify something along the lines of "shed light in 20 feet." And thematically it makes sense that the twilight cleric would make an area of twilight. But I don’t know if the wording is strong enough to imply that it resists attempts to otherwise illuminate the area. (such as from the sun).