Submitted by cmichel, also found by s1m0 and 0xRajeev
There are ERC20 tokens that may make certain customizations to their ERC20 contracts.
One type of these tokens is deflationary tokens that charge a certain fee for every transfer() or transferFrom().
The deposit() functions of Insurance and TracerPerpetualSwaps assume that the external ERC20 balance of the contract increases by the same amount as the amount parameter of the transferFrom.
The user is credited the full amount without the taxes (userBalance.position.quote).
Recommend as one possible mitigation, measuring the asset change right before and after the asset-transferring functions.
raymogg (Tracer) confirmed but disagreed with severity:
cemozerr (Judge) downgraded severity from 2 to 1:
