What are the potential issues with variable naming conventions in PHP, as seen in the provided code snippet?

The potential issue with variable naming conventions in PHP is that they may not be descriptive or consistent, making the code harder to read and maintain. To solve this issue, it's recommended to use descriptive variable names that follow a consistent naming convention, such as camelCase or snake_case.

// Original code snippet with inconsistent variable naming conventions
$usrNm = "John";
$eml_address = "john@example.com";

// Improved code snippet with consistent and descriptive variable naming conventions
$username = "John";
$email_address = "john@example.com";