https://www.desidime.com/discussions/sbi-reward-points-cconfusion?page=1#post_9031648
May be deduction for discount
Kindly, check my sbi reward points there are 0 points redeemed or expired but the closing balance is reduced to 8820
We can check if only you post here statements from September 2022.
Or go through other posts about SBI points deduction and try to understand whats happening
Or write / tweet to sbi support.