I have a section description in a specific course that can't be edited. When opening, the three loading dots of TinyMCE keep showing and TinyMCE doesn't load.

It's difficult to reproduce and it only happens in one section, but here are the errors.

Uncaught TypeError: controller.registerEventListeners is not a function
    at editsection.php?id=350635&sr:2684:16
    at Object.execCb (require.min.js:5:12861)
    at b.check (require.min.js:5:6615)
    at b.enable (require.min.js:5:9363)
    at b.init (require.min.js:5:5721)
    at require.min.js:5:11235Understand this error
first.js:990 Starting Moodle session timeout warning.
tinymce.js:1175 Uncaught (in promise) InvalidCharacterError: Failed to execute 'setAttribute' on 'Element': 'left;"' is not a valid attribute name.
    at rawSet (tinymce.js:1175:13)
    at tinymce.js:1187:9
    at each$d (tinymce.js:457:9)
    at setAll$1 (tinymce.js:1186:7)
    at shallowAs (tinymce.js:5622:7)
    at mutate (tinymce.js:5626:18)
    at processNode (tinymce.js:16999:11)
    at Object.sanitizeHtmlElement (tinymce.js:17114:13)
    at parseAndSanitizeWithContext (tinymce.js:17298:19)
    at Object.parse (tinymce.js:17361:25)