So, trying to figure out what's causing this error because Phar is installed and active. But have now tried with PHP56, PHP73 and PHP74 and I get same results on version 90.0.5.
And first 5 lines of the wp-cli.phar is:
Any help to solve this would be really nice! 
Code:
Fatal error: Uncaught Error: Class 'Phar' not found in /usr/local/cpanel/3rdparty/share/cpanel-wp-cli/wp-cli.phar:3
Stack trace:
#0 {main}
thrown in /usr/local/cpanel/3rdparty/share/cpanel-wp-cli/wp-cli.phar on line 3
Code:
#!/usr/bin/env php
<?php
Phar::mapPhar();
include 'phar://wp-cli.phar/php/boot-phar.php';
__HALT_COMPILER(); ?>