In Impress if I type on blah blah November 12th is blah. Impress goes into superscript at the start of the 12, and stays in it. I assume this is a bug.
I don’t recall having seen this behavior in all 4.2 versions I used, I also get a correct swithing back to normal positioning of character following a string like “November 15th”.
Please also read first and update your question. To provide an answer more information is needed. Please have a look at What information should I include in a question in addition to OS and LibreOffice version? - #4 by ROSt53