After installin PublishPress Revisions i see some differences between a wp installation and a PB installation
is there any reason why the update revision button is not available in a PB installation?
Do PB hide some type of code?
Yes – in Pressbooks 5.0 we replaced the standard WordPress publish panel with a custom Status & Visibility panel. See https://github.com/pressbooks/pressbooks/commit/825e5850d8c06ce0a72657611dd936785f6ee4f5 and https://github.com/pressbooks/pressbooks/blob/32d42d579604186cd2e5dc609b60b1a611f2e72b/inc/admin/metaboxes/namespace.php#L764-L919