1
L SEP
is a non breaking line space that is not supposed to shown to the user. How you are seeing it varies, but typically they appear when they aren't stripped out of content prior to making it into a database/cms/etc. Almost every one I've ever seen in the wild has been a result of writing content in Word and then copy/pasta the content into an HTML document, without sanitizing anything.
The reference below has a jQuery solution to target this character:
ref