What will happen to those currently unstaking BNB?

If the user unstaked before block 23545403 he will get his BNB, if user unstaked after block he will get his amount of tokens (aBNBb/aBNBc) that was on his balance on the block 23545403.

Users that redeemed aBNBc or aBNBb (unstake) before the exploit (see block height above), will receive BNB at the end of the unbonding period. Users that redeemed aBNBc or aBNBb after the exploit, will not receive BNB at the end of the unbonding period and will get an ankrBNB airdrop.