flmngr
Flmngr is a module for Drupal which has deep integration into the CMS. It will automatically attach the file manager to all your file choose fields, and place its buttons onto the CKEditor toolbar (configurable individually on each text format).
Flmngr file manager adds to your CKEditor 4 and CKEditor 5 an ability to upload files and images, manage them, and many other functions you expect to find in a file manager.
For CKEditor 5 users: do not forget to add the Flmngr buttons to the toolbar inside the "Full HTML" text format.
Drupal 10.2 notice: update Flmngr and all its dependencies to the latest versions. Otherwise file browsing won't work.
Flmngr also has a built-in image editor with crop, resize, and transform tools and search over 30K free stock photos from Unsplash.
Flmngr works with your own server storage (for free) but has also an optional paid feature to work with Amazon S3 bucket or Azure Blob container.
Flmngr is built for excellent Drupal 10, Drupal 9 and Drupal 8 integration: it does not need any configuration; it deploys its server part automatically and links it to CKEditor; it also checks user permissions to prevent unauthorized access (by default it denies access to modify files to website visitors except administrators). Wherever you use CKEditor 4/CKEditor 5 to edit content, you will be able to upload files and manage them there too.