We have also an issue with this, from our Theme builder I get the following description:
It’s bug of yoast seo plugin. You can report to author of plugin about issue
Here is console
Uncaught TypeError: Cannot read property ‘setAttribute’ of undefined
at i.aria (theme.min.js:1) https://****/wp-includes/js/tinymce/themes/modern/theme.min.js?wp-mce-49110-20201110
Write to them that you have problem with text editor in category descriptions
It looks great yes, but I want to use the other theme because there are more options available. So can you take a look what causes the lay-out problems?