Submitted by Shield, also found by ladboy233
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L138-L142 
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/TaikoL1.sol#L209-L211 
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L83 
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L93 
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L101
The LibDepositing.depositEtherToL2 function is called by the TaikoL1.depositEtherToL2 to deposit ether to the L2 chain. The maximum number of unprocessed eth deposits are capped at _config.ethDepositRingBufferSize - 1 as shown here:
The Taiko configuration states that ethDepositRingBufferSize == 1024. Hence the maximum unprocessed eth deposits allowed by the taiko L1 contract is capped at 1023.
When the L2 block is proposed by calling the LibProposing.proposeBlock function by the TaikoL1 contract,  it processes the unprocessed eth deposits by calling the LibDepositing.processDeposits. But it is allowed to process at most 32 eth deposits per block as per the following conditional check in the processDeposits function.
Here the ethDepositMaxCountPerBlock == 32 as configured in the TaikoL1.getConfig function.
And the fee amount for each of the eth deposits are calculated as follows:
Hence the deposited eth amount is deducted by the calculated _fee amount for the eth deposit transaction. If the basefee of the L1 block increases significantly then the maximum fee of ethDepositMaxFee: 1 ether / 10 will be applied. Thus deducting that amount from the transferred eth deposit to the recipient in L2.
Now lets consider the following scenario:
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L138-L142
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/TaikoL1.sol#L209-L211
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L83
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L93
https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/L1/libs/LibDepositing.sol#L101
VSCode
Hence it is recommended to add a slippage check for the fee amount of the deposited eth amount in the LibDepositing.processDeposits function, since depositEtherToL2 and processDepositare two different transactions with a delay during which the L1 block basefee can increase significantly causing loss of funds to the recipient in the form of fee increase.
dantaik (Taiko) acknowledged, but disagreed with severity and commented:
0xean (Judge) commented:
