A number of things could have caused this, but I would need you to contact support as nobody here can see your account.
Things that can reduce your deposit:
Square Fees - The fees you pay to receive square payments
Charge Backs - Customers have claimed fraud transactions and this money is being disputed
Refunds - A refund issued even the previous day (or during this time period) could cause you to owe Square money
Square Loan - Fees are deduced per transaction
Your customers paid in Cash or other formats than Debit & Credit
Currency Exchange - You are operating in one currency but your account is in a different
Human Error - Your transaction history could contain an error causing things to be artificially inflated
There are other less common causes, but Square support and your private transaction records will paint a complete picture when you reach out
