how to disable CodeMirror?

Go to your profile in /wp-admin and check the option to disable syntax highlighting. That should disable CodeMirror.

For what it’s worth, I completely agree with you about CodeMirror. I’d even go so far as to say that the WP devs broke their own credo by adding it to core — it is IMO a classic case of something that should be a plugin. It’s also somewhat hypocritical…why go through all the effort of discourageing people to edit code from within WordPress, and then add something to make the task easier (for some people, anyway)?

The new linting code is IMO in the same category. If you really want to discourage people from editing code within WordPress, then let those people wreck their site! ??

Oh, sweet. Had not noticed that setting. Done and done. Thanks.

It also kills the useless search feature where if I search then edit one instance of something, I have to restart the search from scratch.

@diondesigns you are a life-saver and I owe you a drink. Along with being one of those old-timy “get-off-my-lawn” developers, I also use a screen reader, and at the moment Codemirror is completely inaccessible if you use any assistive technology, although they are working on fixing it. And despite my being one of the loudest advisors against so-called cowboy coding, there are rare occasions when I actually need to do it. So thank you a ton for answering this question. Disabling syntax highlighting reverts things back.