But it appears the built-in version of TinyMCE is version 4.9.11 (2020-07-13)
End of support (bug fixes, security) was reached for that version a while ago and it is recommended to use version 6 now: https://www.tiny.cloud/docs/tinymce/6/
Is there a plan to update to the latest version of TinyMCE?
Our plugin doesn’t load a custom version of TinyMCE, but the built-in WordPress one (via this function wp_editor() – Function | Developer.WordPress.org). Please try contacting WordPress support regarding this, I’m not sure if they plan to continue TinyMCE support and update the script included with WordPress. you can also try using a plugin like this one Advanced Editor Tools – Wtyczka WordPress | WordPress.org Polska Maybe they load the latest version and replace the WordPress one.