Nextcloud photos displays selected picture in thumbnail dimension

Hello there,
I am facing an issue where the Nextcloud photos browser app displays all my pictures in small dimensions, it seems like it just displays thumbnails. When I download a picture from the side menu, I always get the real image instead of its thumbnail, so it is not a file issue. I tried to find a solution on the forum :
I tried to change the preview_max_x and preview_max_y in the config.php file, but it doesnโ€™t make any change. I have Nextcloud 28.0.2 and previewgenerator is