Pinky Finger Conundrum

Kunal, I'm with your masterclass instructor that raised pinkies always strike me as little red flags waving in the air to call attention to tension. But that said, I've seen so many high caliber pianists play with passages like you describe with the kind of stiff or raised pinky that I would usually call my students on, so I'm prepared to accept I don't fully understand the role of tension here and what is an acceptable amount in a given situation (found your topic because I was indeed searching for some other pinky thinking!).

All that said, if this is something you're interested in improving, I would suggest breaking your fast passages into small pieces with little breaks, and giving yourself a chance to check in with your fingers and see if they're still relaxed before and after. e.g., in a string of sixteenths, could you play 4 sixteenths plus the first note of the next beat without the pinky popping up? If not, go smaller! But if you can, then maybe chain two beats worth of 16ths, but still with pauses, to check in with your fingers. You are training yourself to recognize tension and let it go. Let this happen slowly at first and as you work at it, you'll get better at recognizing the feeling and coming back to the "neutral" feeling that lets your pinky rest when it's not needed. Good luck!