Xdebug3 can't be triggered on PHP8.x after enabled

Issue

Environment is on PHP8.X, Xdebug3 cannot be triggered after enabling Xdebug by Acquia Support.

Troubleshooting

Check if Xdebug version is 3, be aware that there will be two versions of Xdebug - version 2 for PHP 7.4, version 3 for PHP 8.0+. Use the below command line to check Xdebug version:

app@staging-xxxxx:/var/www/html/app.env/docroot/sites/default$ PHPRC=/mnt/www/site-php/<appenv> drush --uri=www.example.com ev "echo phpversion('xdebug');echo PHP_EOL;"

3.0.2

Check , if xdebug.mode is on develop mode as per the document of `https://xdebug.org/docs/upgrade_guide`, it needs to be set to debug mode..

app@staging-xxxxx /var/www/html/app.env/docroot/sites/default $ php -c /var/www/site-php/<appenv>/php.ini -i |grep xdebug.mode
           Enabled Features<br/>(through 'xdebug.mode' setting)
xdebug.mode => develop => develop

Resolution