This is due to the All Caps font formatting. Sometimes text in documents which appears to be in upper case is actually in lower case but formatted with the 'All Caps' font format in Word. To make matching more intuitive, by default, O&D replaces 'All Caps' formatted text in the document with actual upper case letters before operating on the document. Due to this text is appearing modified.

If preventing this from appearing in redlines is required for your workflow, you can disable this automatic conversion toggling of Convert 'All Caps' which is located within the Editing options within the toolbar.

Warning: Disabling Convert ‘All Caps’ can make matching confusing when the ‘Match Case’ editing option is enabled, as it can result in letters that look like uppercase letters (due to the font format) being treated like lowercase letters (because they actually are).