First of all, tell me your character that you’re using.
I’ll start off by saying that I never have this problem with Cammy because once I see Ibuki going for her vortex, I immediately Cannon Spike, because of the trajectory, it beats air Kunai AND autocorrects in some cases, or in other cases, it simply gets me out of the situation safely. You have to realize that 100% of competent Ibuki’s WILL get you trapped in this after a knockdown. Pay attention to where they throw their Kunai from, and make sure and block Ibuki and not the Kunai, even if she crosses past your body (which can be hard to tell).
If you are really having trouble seeing where to block, dash/backdash on recovery. It will still hit you down and tech you, but at least its a techable knockdown and you can get up faster than Ibuki can start her next vortex.
Another Idea is to throw out an abiility on wake-up that has invincibility frames to protect you. The key is to not get knocked down, but in the case where you do (and most likely will), Pay attention to where Ibuki throws her Kunai from and block HER, unless of course she crosses over you, then you are obligated to BLOCK main on the other side(similar to Dhalsims Fireball Teleport)
But Usually all reversals that are DP in form beat Ibuki’s vortex, if done correctly, or at the very least, gets you out of trouble safely. I’ll admit its hard to judge using a character that doesn’t have a reversal, but maybe this might be something you’re going to have to set up in training mode.