Latest/highest possbile PHP version for cakePHP 2.8.5

I use a legacy application that uses cakePHP 2.8.5
I can’t change that application or upgrade cakePHP to a higher version.
I will however have to upgrade the PHP version on server which currently PHP 5.something.
How high can the PHP version be and still not break cakePHP 2.8.5?
in version PHP 8, I get the following error:
PHP Fatal error: Cannot use ‘Object’ as class name as it is reserved in /var/www/qrop/Vendor/cakephp/cakephp/lib/Cake/Core/Object.php on line 30
which is an error you get from PHP 7.2 and above

FYI: CakePHP 2 is EOL since June 15, 2021 and therefore won’t recieve any further PHP support updates.
But there are other people forking cakephp 2 and making it PHP 8.0/8.1 compatible which you can find in e.g. this Github issue.