There can be several reasons why a pending deposit transaction may disappear. Here are some possible explanations:

1. Transaction expiration or cancellation: Sometimes, a pending transaction may disappear from your transaction history if it expires or gets canceled by the merchant. This means that the transaction was not processed and the amount is returned to your available balance [1].

2. Processing delay: In some cases, pending transactions may take longer to process and may temporarily disappear from your transaction history. This can happen due to various factors such as merchant processing times, security checks, refunds, or payment amount adjustments. Additionally, holidays and weekends can also cause delays in processing pending transactions [2].

3. Technical issues: Occasionally, technical issues can cause pending transactions to disappear temporarily. These issues may be related to the bank's systems or the merchant's systems. If this happens, the transaction may reappear once the technical issue is resolved [3].

It's important to note that the specific reasons for a pending deposit transaction disappearing can vary depending on the circumstances and the policies of your bank or financial institution. If you have concerns about a specific transaction, it's best to contact your bank or credit card issuer for further clarification.

Learn more:

1. What are pending transactions - CommBank
2. How Long Do Pending Transactions Take To Expire? | MoneyLion
3. deposit disappeared from my bank account?