Is there any receipt to prove the payment via bank transfer?

There are many ways to make bank transfers, including wire transfer, clearing, etc.

According to your description, it should be a remote wire transfer from an individual to a public account.

So, if you use cash, the bank will give you a business receipt stamped with "Cash Clearance". Usually, the special stamp for cash clearance is square, but some banks have round or octagonal stamps. Anyway, there is a cash clearance message.

If you use bank card transfer, the bank will give you a business receipt stamped with "Transfer". Normally, the transfer stamp is triangular.

In short, you will receive a receipt, and be sure to have it stamped by the bank. If some banks do not give you a stamp due to service problems or attitude problems of the business staff, you can ask them to stamp the bank seal to show acceptance.