the debuff came in the same patch as xp-off queues, i feel like this is specifically design to fill that gap (beyond nerfing 110-120 leveling in isles), at the same time it reduced xp-off activity, nobody ever got in trouble for debuffing that i know of, since patch 8.2 where this was introduced
You can keep reporting but idk, one time i tried to ask in the official forums if that was a exploit or not and i got my post deleted, but i've saw other people talk about it in the official foruns and nothing happening
chances are, you prob will never get in trouble for debuffing but this should get fixed at anytime
Also people can xp-on in the queue without going random bgs, queueing for specific (so there is not xp-bonus for winning) and quitting before the bg ends, if you're a 27 you can do like more than 100bgs until you cap 30's