When String properties that can contains newlines (like text() for QString) are output to a ui file, some other editors may decide to reformat it and change the format of the string, in particular it may add spaces and other newlines that will alter the original string.
For example, I have a QLabel with text() value like "Firstname\nLastname".
The \n character is expanded to newline in the UI file.
If I load it in some other editor, it might legitimally reformat it and add a second newline and an indent.
It is legit.
To prevent this there are two options:
1) surround the text with a <![CDATA]> tag, or
2) use an xml:space="preserve" attribute to the <string> tag.
Both work with the editors I tested, i.e. jetbrain's clion.