Is the KF miles required for a flight fixed? For eg, I nd 50k miles to redeem flight from SG to 'X' & it costs $600. 3 mths later, the same flight costs $800. Will the miles required change too?

Asking this because flight prices tend to increase closer to the date of your flight. So i'm not sure if this affects the miles required. I've never redeemed KF miles before, so sorry if this is a potentially dumb qn!