Easy to check: create a Text, Pages or Word document with a unique name in it, but give it an innocuous filename. Then do a search for the name inside the document. I haven't tried it yet on my end but I'm pretty confident that Spotify will find the name 😉
Edit: I did a quick check but results are inconclusive so far. I tried some strings that should hide in various documents across my drive, but did not get all the results I was expecting. More research needed!