PhpStorm find all deprecated usages in the project
Code | Analyze Code | Run Inspection by Name... (Ctrl + Alth +Shift + I here on Windows using default keymap) -- search for "deprecated" and choose the most correct one for your needs.
https://www.jetbrains.com/help/phpstorm/2021.2/running-inspections.html#run-one-inspection
This will work as long as new Symfony is already in the project (so that the IDE knows what method/class/constant is now considered deprecated (based on @deprecated PHPDoc tags)).