mediapicker field is not displayed as it should anymore

I worked on a GRAV 1.7.26 (PHP 7.4.8) website with custom admin tab including a mediapicker field. The mediapicker displayed well.
Since I updated GRAV to 1.7.39.X with all plugins, the mediapicker is not displayed as it should anymore.
The scrollbars are not included (the modal scrolls) and the lists (tree and media) are displayed after the container.

I tried to install a fresh GRAV site and test the mediapicker field in the admin and I have the same result :
[Enregistrement 2023-02-20 221529.webm](https://user-images.githubusercontent.com/99741942/220217391-cb44eadd-5f9c-4d8b-a8e5-877cdeb97fb7.webm)

I tried to exclude the admin from the flex objets directory but it only let me see the folder's tree.

I saw that the code changed a lot between those two versions, particularly with the scrollbars and the way the medipicker is displayed in the modal but I can't correct it myself.