String-only methods ignore vararg arguments.

[CedNaru]

It seems we forgot to take into account vararg parameters when we generated the String-only (using String instead of StringName and automatically cache them) when implementing those new helpers.
You can find an example here:

godot-kotlin-jvm/kt/godot-library/godot-api-library/src/main/kotlin/godot/api/SceneTree.kt

Line 811 in aa8e09c

) = callGroup(group.asCachedStringName(), method.asCachedStringName(), )

Where the vararg should be written is instead left empty.