We recently restored our Magento Database, and upgrade the Magento from 2.3.0 to 2.3.3. And I noticed that some of the newly registered customers associated with an old order. So the customer can see other's order info. As you can see from the picture below, this customer is newly registered in Jan 2020. But there is an order placed May 2019 associated with this account. This is just an example. There are more accounts associated with an order that does not belong to that account.
We tried to delete all the customer information. But this does not fix this issue. Any idea how to fix this? Thanks for helping.
