Hi Antoine
We have identified the issue: https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Image%21Image.php/function/Image%3A%3Aresize/9.2.x was introduced as part of Drupal 9.2.x, and is causing the stretching you are seeing now. We will apply patches to our CERN themes to avoid this happening. Once done, updates will be pushed centrally. No further action is necesarry from you on this one.
In regards to the modules, please be advised that we only support the Webform module (not any extensions or related modules). As such, if you absolutely require the functionality from these modules, you will either have to adopt the module(s) in question or find alternative ones. However, we are keenly aware that many websites utilise the Webform module alongside addon modules. We are looking into what we can feasibly done in the longer-term.
Thanks!