JNB Token Rug Pull

What the code allows:

1. Every transfer to or from the pair address pays a fee debited from the sender's balance: uint256 TFee = amount.mul(buyTaxFee).div(100); followed by doTransfer(from, address(this), TFee);. As deployed buyTaxFee is 15 (the source comment says 2%), and it applies to sells as well as buys because the check is if(from == uniswapV2Pair || recipient == uniswapV2Pair).
2. The owner can set that fee to any uint8 value with setbuyTaxFee; there is no cap. At 100 the whole amount goes to the contract and the recipient of the trade receives 0; above 100 the amount.sub(TFee) step reverts, so trades through the pair fail.
3. The owner can blacklist any address with addBlackList or setIsBlackList. _transfer requires isBlackList[from] == false and isBlackList[recipient] == false, and transferFrom passes the holder as from, so a blacklisted holder can neither sell through the router nor receive tokens.
4. Before every transfer to the pair, _transfer calls swapRewardToken(), which computes _balances[address(this)].mul(exchangeFee).div(100). The owner can set exchangeFee above 100 with setexchangeFee; the swap then tries to move more tokens than the contract holds and reverts, which blocks every sell while the contract holds any fee tokens. Buys (from == uniswapV2Pair) do not call it. With exchangeFee at or below 100 the routine sells that share of the collected fee tokens for USDT and sends it to walletTax with a minimum output of 0, and walletTax is owner-settable.
5. The owner can also pull any token or the BNB held by the contract with rescueToken and rescueBNB.

6. CertiK reported on February 28, 2023 that two EOAs sold JNB for about 106K USD in total and the price fell more than 98%. The sources opened do not show whether the blacklist, fee or exchangeFee controls were used in that event, or the relationship between the two sellers and the deployer 0x06d19456…CeeA64.