Tell us what you are trying to do?
Get back to the previous version of a post.
Is there any documentation that you are following?
Not really. I understand that the latest update of WP made Revisions not visible in Classic Editor, only in Gutenberg. But I don't know how to get Gutenberg back. I have the plugin Classic Editor and set it for an option. But it doesn't work
Is there a similar example that we can see?
Attached an image.
This appears to be a problem specific to Types, where revisions for custom post types registered with Types are not showing at all, whether in the Gutenberg editor or the Classic editor.
I've been testing this, and can see that it works fine on the prior WordPress version (5.4.2) but breaks with WordPress 5.5.
I'm escalating this so that we can take a closer look to understand why, and I'll get back to you with any feedback as soon as I can.
If this is proving an important limitation for you, you could try a plugin to roll back to the previous version of WordPress in the meantime (after taking a backup), e.g. https://wordpress.org/plugins/wp-downgrade/