Thanks for pointing out Gain or Oanda, I don't use them. Nonetheless, it must then be a serious issue with one or some of their liquidity providers. 2% is not 10 or 30 pips. And IB is not fxcm or gain or Oanda. I think you would be equally concerned would you trade in size and had a 7 second price spike wiping out your position at a large loss.
Check the other DKK pairs - big spikes at the same time on other DKK pairs appearing at other tier-1 Fx brokers like Gain Capital & Oanda.
This is clearly not an IB issue.
NOK/DKK -5.8% spike
EUR/DKK -3% spike
USD/DKK -1.7 spike
View attachment 187639