qlstephen is a mac os quick look plugin used by macvim to allow users of mac ox to quick view text files with no file extension.

the quick look plugin config file that comes with krita to quick look at .kra files has a seemingly unneeded key which blocks the qlstephen plugin from working.  

after installing krita, there are quick look warnings in the console, warning that a plugin is shadowing another, it's most likely the public.data key

you can enable quick look logging with:
  defaults write -g QLEnableLogging YES

by deleting the CFBundleDocumentTypes > Item 1 > LSItemContentTypes > public.data key from the krita quick look plugin's Info.plist  I was able to restore the functionality of qlstephen to normal, without seemingly effecting the krita quick look plugin.  I restarted the machine and tested again and both file formats now go to the proper quick look plugin.

https://i.imgur.com/XSDq8nx.png