If you see your names appearing squished together on your booking, this is OK! Many airlines have reservations systems that do not have a middle name field or fields for multiple last names, so once your ticket is issued, their automation system automatically pushes your names together. This can also happen if your name has a lot of characters.
Example of name correctly entered in the app:
Harry James Potter
How it might look on the airline's website:
HARRYJAMES POTTER or HARRYJAMESPOTTER
This is OK! As long as your entered your name correctly in the app and it appears in the same order as your travel document (passport, driver's license etc.), you shouldn't have any problem checking in at the airport.