No I do not use WordFence, but I guessed right. The message WP.org shows for old plugins is this:
This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
I know it still works in classic editor with classic editor plugin installed. On current WP versions. So despite it being abandoned why not just keep using it if it works? With the focus on Gutenberg, Classic Editor probably will not move very fast, so it will probably continue to work. There are however issues reported on the support forums for it but related to ARVE. But I have not heard any issues from users about it for a very long time.
I do not know any other options for this, there are probably none.
But you can just deactivate it, all the posts with arve shortcodes will continue to work. You just lose the previews and shortcode editing on the backend if you disable Shortcode UI. As the name suggests it’s just a UI (User Interface) for creating shortcodes and displaying a preview in Classic Editor. It does not interfere with functionality of the underlying plugins that provide the shortcodes.