Yes, indeed this is the problem with this change.
In some cases log(x) term won't be included in big O notation. This is because when log(x) is replaced by logx paramter, the order term ignores it.
That is why, O(x**4*logx**4) is evaluated as O(x**4) which is wrong.

But I don't find any other way to fix this issue other than passing the logx parameter.
Maybe we need to change the Order class such that it includes the logx parameter too.