Salesforce Flow Variables Lose Values Navigating to Previous Screen

Create a screen flow with some input fields on the Screen-1. Assign a value to a variable based on the inputs on ‌screen-1. It could be any data type. Now navigate to the next Screen-2, and click "Previous" button to return to the first screen. Observe that the variable loses it's value assigned to it via the input screen. Although the input screen might still retain those values.

In another scenario, save values from input screen-1 into a variable and perform a DB operation to insert/update a record and display screen-2 with record values. Now navigate to the previous flow screen by clicking the "Previous" button. Although the DB operation is complete and the record is inserted/updated. Observe that the variable, which was assigned values from screen-1, goes NULL. This may cause problems if we use it in a decision element to check whether the record in the first step was already created/updated or not, while moving forward again.