How to define a rule in functions.php that ONLY disables the default wp functionality that undesirably changes ‘&’ to ‘#038;’?

How to define a rule in functions.php that ONLY disables the default wp functionality that undesirably changes ‘&’ to ‘#038;’?

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)