Help! Formatting stripped from WP Post editor following latest update

Early last week, WP pushed a software update, after which all formatting was removed from the blog post WYSIWYG editor.

Now, everything I write looks like plain text. This includes headlines, headers, and of course, plain text. To be clear, the formatting code is still in there, i.e. if I apply formatting to my post it's there, but invisible until I preview or publish the post.

This is super annoying from an editing standpoint. Has anyone else noticed this problem, and if so, did you find a way to fix it?

For the record I'm using Windows 11 Home, version 23H2 in Chrome browser.