I have a few problems with JCE Editor in Joomla 4:

- The File browser is only visible on the screen as a very small window. See the image: JCE Editor-File browser.JPG
- Within the Current Editor Layout, all icons are displayed in one column, rather than in rows. See the image: JCE Editor-Current Editor Layout.JPG
- In the Editor Parameters screen I cannot use the tabs Typography, Filesystem and Advanced. See the image: JCE Editor-Editor Parameters.JPG

How can I solve this? I already reinstalled the extension, but that did not help.

I will check it...

I've made some changes now. I copied the Admin Tools settings from a Joomla 3.10 installation and now everything seems to work!:D

As @deroderuiter found after the tip @Ryan gave, the issue relates to .htaccess file generator settings in Akeeba Admin Tools. Add:

administrator/components/com_jce

To Admintools .htaccess generator in the "Allow direct access, except .php files, to these directories" section, and it will allow the CSS files that are being blocked to be loaded.