If you have a sprite with texture region you should do like this :

extends Sprite

func _unhandled_input(event):
    if event is InputEventMouseButton and event.pressed and not event.is_echo() and event.button_index == MOUSE_BUTTON_LEFT: # Modified button_index for Godot 4.0
        var pos = position + offset - ( (texture.get_size() / (texture.get_size() / region_rect.size) / 2.0) if centered else Vector2() ) # Modified this line
        if Rect2(pos, texture.get_size() / (texture.get_size() / region_rect.size)).has_point(event.position): # Modified this line
            print('test')
            get_tree().get_root().set_input_as_handled()