What are the potential issues with using deprecated PHP functions like "eregi_replace" in PHP 7 or 8?

Using deprecated PHP functions like "eregi_replace" in PHP 7 or 8 can lead to compatibility issues and may result in errors or warnings being displayed. To solve this problem, you should replace deprecated functions with their recommended alternatives. In this case, you can replace "eregi_replace" with the "preg_replace" function, which provides similar functionality but is not deprecated.

// Deprecated function
$string = "Hello, World!";
$pattern = "/hello/i";
$replacement = "Hi";
$result = eregi_replace($pattern, $replacement, $string);

// Updated code using preg_replace
$string = "Hello, World!";
$pattern = "/hello/i";
$replacement = "Hi";
$result = preg_replace($pattern, $replacement, $string);