Flow

Summary
The protocol has stated that ERC20s interacting with the protocol should have a total supply below, however the standard specifies up to 256 bits and therefore values above 128 bits should be handled(capped) to ensure the protocol maintains its 256 bit cap whilst also ensuring that no party loses their funds

Vulnerability Details

There are two instances where this vulnerability occurs
https://github.com/Cyfrin/2024-10-sablier/blob/8a2eac7a916080f2022527408b004578b21c51d0/src/SablierFlow.sol#L811

https://github.com/Cyfrin/2024-10-sablier/blob/8a2eac7a916080f2022527408b004578b21c51d0/src/SablierFlow.sol#L473

the above code reverts if totalDebt > type(uint128).max
this could mean that users might not be able to execute core functionalities like withdraw or refund if the supply of ERC20 token surpasses 128 bits, and the debt also surpasses 128 bits
A better approach would be to cap the debt at type(uint128).max
something like
debt > type(uint128).max ? type(uint128).max : debt

Impact

User funds could be locked

Tools Used

Recommendations
Protocol values should be capped at type(uint128).max rather ]than reverting if it passes that value