The developers learned the lesson that they should understand the libraries they are using, and they made a new version.
In the new version BankV5, they decided to use WETH instead of USDT, with simple logic for deposit and withdrawing.
They launched there bank on Ethereum, everything is find, users are depositing and withdrawing easily, and no attack or unintended behavior occurs.
After a while, the number of Bank users increases, and it becomes a popular Bank on Ethereum BlockChain. The developers' business is growing, so they decided to extend their busniess and deploy their bank on Arbitrum.
After deploying on Arbitrum, and users starts using it on Arbitrum, they receive messages from clients that they are unable to withdraw their tokens. The Bank Developers are shocked by this as the Protocol is working fine on Ethereum, and withdrawal is not working on Arbitrum.
You need to know what is the problem that prevents withdrawing functionality from working on Arbitrum.