Different behaviour between RenderTree(root) and RenderTree(root).by_attr(lambda x: x)

[epistoteles]

I have a custom Comment class inheriting from NodeMixin.
This class has a custom __repr__ implementation producing a string with two newline characters:

def __repr__(self):
    return f"▲ {self.score} {italic(self.author)}\n{color(blocked(underline(self.title)), c='yellow')}\n{color(blocked(self.body), c='yellow')}"

When I print the root node using print(RenderTree(root)) I get the following (undesired) output:

However, when I print the root node using print(RenderTree(root).by_attr(lambda x: x)) I get the following (desired) output:

The lambda function should not have any effect. Why do the two outputs look different?