Why the columns appear like that ??
They are not corretly align with the table
They are aligned in spreadsheet format as far as I can see. Numbers align right, characters align left.
Actually, this is meaningless in an R data.frame or tibble. If you need the data formatted for publication you do it using a package such as xtable or kable.
If you are concerned about the header alignment with the columns, I wouldn't worry too much about it. I normally see this when I am viewing a tabular dataset with long columns names or lots of columns. I suspect it has to do with how much memory the add-in is allowed to use.