my sudoku web script needs fixing -- 3

I have a sudoku webscript written in php javascript.this web script needs fixing as recently after upgrading from php 5.6 to php 7.4. each time it does not change into new game. each time when i press play again button, it keeps showing the same game. please try : math-ib.com ----> login -----> usr: principal pw: 123 try sudoku 9X9---> play and try play again