Hey.
Its all in the title. I play on Non Ranked but i get still XP and reached lvl6 (from 5).
Bug or Feature?

I think it's intended, but you don't get any weapon/attachment unlock points and no experience from challenge rewards like killing 150 people with the scar.

The weapon unlocks work correctly on ranked but you can still get the unlock tokens in unranked but they wont stick. You have to get them in a ranked server and also Unranked will not track and transmit to the leaderboard.