Submitted by R2, also found by kyteg
https://github.com/code-423n4/2022-11-redactedcartel/blob/03b71a8d395c02324cb9fdaf92401357da5b19d1/src/vaults/AutoPxGlp.sol#L367
https://github.com/code-423n4/2022-11-redactedcartel/blob/03b71a8d395c02324cb9fdaf92401357da5b19d1/src/PirexGmx.sol#L583
In PirexGmx and AutoPxGlp you have function depositGlp(), which accepts any ERC20 token from whitelist.
Now there are 9 tokens (see here: https://arbiscan.io/address/0x489ee077994b6658eafa855c308275ead8097c4a#readContract):
WBTC, WETH, USDC, LINK, UNI, USDT, MIM, FRAX, DAI
And the list may extend
So any user can deposit any of those tokens and receive pxGlp token:
But if any of these tokens will start charge fee on transfers, the logic will be broken and calls to depositGlp() with suck token will fail.
Because here you use the amount of tokens sent from user wallet: https://github.com/code-423n4/2022-11-redactedcartel/blob/03b71a8d395c02324cb9fdaf92401357da5b19d1/src/PirexGmx.sol#L512
And then gmxRewardRouterV2 tries to transfer tokens to his balance from your balance:
(See https://arbiscan.io/address/0x321f653eed006ad1c29d174e17d96351bde22649#code - GlpManager and
https://arbiscan.io/address/0xA906F338CB21815cBc4Bc87ace9e68c87eF8d8F1#code - RewardRouterV2)
But you received less than tokenAmount tokens because of fee. The transaction will fail.
Lets imagine USDT in arbitrub started to charge fees 1% per transfer.
Alice wants to deposit 100 USDT through PirexGmx.depositGlp()
Then you do
t.safeTransferFrom(Alice, address(this), 100);
You will receive only 99 USDT
But in the next line you will try to send 100 USDT:
So transaction fails and Alice cant get pxGlp tokens.
VS Code
USDT already has fees in other blockchains.
Many of these tokens use proxy pattern (and USDT too). Its quite probably that in one day one of the tokens will start charge fees. Or you would like to add one more token to whitelist and the token will be with fees.
Thats why I consider finding as Medium severity.
To avoid problems, use common pattern, when you check your balance before operation and balance after, like that:
drahrealm (Redacted Cartel) confirmed 
Picodes (judge) commented:
