Watchdog vardumper does not work

Problem/Motivation

I installed Vardumper module, with the Symfony var-dumper selected for Devel, but in the log event detail page, the dumped data does not have the correct format. I'm just trying to log an array with one element.

Could you help me ?

My Drupal Core version is 9.5.2, PHP 7.4.29 (Could it come from that ?)

This is my first issue, sorry if it's messy or not clear