spacing between lines in mac applications changed unexpectedly

My colleague has an issue on their MacBook Air where all of a sudden the spacing between the lines in different applications on the Mac has increased, in the following apps - Mail, What's App, folders in Finder, Messages, reading newspapers in Safari, and the text in What's App has increased.

I looked at the resolution settings and tried changing them to default but that just made everything tiny, the issue isn't to do with the text size, it's the spacing between the lines - like in Word when you change spacing to 1.5 line spacing - except this isn't in Word, it's in all the system applications.

Has there been an update or system change that would affect the spacing between lines that would be noticeable to a user, I've searched the internet but can't find anything about this issue?