REDEMPTION doesn’t necessarily mean it’s the end of that particular staking position, nor does SUBSCRIPTION necessarily signal the beginning of staking position. REDEMPTION returns all instances of when you redeemed/withdrew funds from a staking position whereas SUBSCRIPTION is whenever you added funds to a staking position. Eg. on staking products that aren’t locked, you can redeem/remove a portion of your funds from the position at any time which would be recorded as a REDEMPTION event. Similarly you can add funds to a position at anytime which would be recorded as a SUBSCRIPTION event.