Submitted by 0xdeadbeef0x, also found by rbserver, Rolezn, Ruhum, Faith, mookimgo, 0x52, 8olidity, and KingNFT
Traders will not be able to:
If USDT is set as the margin asset and protocol is deployed on Ethereum.
(Note: this issue was submitted after consulting with the sponsor even though currently there are no plans to deploy the platform on Ethereum).
USDT has a race condition protection mechanism on ethereum chain:
It does not allow users to change the allowance without first changing the allowance to 0.
approve function in USDT on Ethereum: https://etherscan.io/token/0xdac17f958d2ee523a2206206994597c13d831ec7#code#L205
In Trading, if users use USDT as margin to:
The transaction will revert.
This is due to the the _handleDeposit which is called in all of the above uses.
_handleDeposit calls the USDT margin asset approve function with type(uint).max.
From the second time approve will be called, the transaction will revert.
_handleDeposit in Trading: https://github.com/code-423n4/2022-12-tigris/blob/588c84b7bb354d20cbca6034544c4faa46e6a80e/contracts/Trading.sol#L652
VS Code
No need to to approve USDT every time.
The protocol could:
TriHaz (Tigris Trade) confirmed 
Alex the Entreprenerd (judge) commented:
GainsGoblin (Tigris Trade) resolved:
