Finding all broken links

My Joplin data got into a bad state (not sure why so this isn't a bug report) so I restored from a cloud backup. This resulted in some notes being deleted leading to broken links (again not sure why, but I'll just move on). I can find those old, deleted notes in my cloud backup when I encounter the broken link in a note. But I've got way too many notes to go through every one of them. What I'm hoping to figure out though is if there's a quick way for me to identify all of the broken links. Is there a plugin which can report this?

I suppose if nothing else I'll write a script against the API to find these. Any pointers on how I could save time doing this?

I cannot be sure that this will work, but have you tried installing the "conflict resolution" plugin, and run a sync again ... BTW, you said cloud backup, which makes me think you are NOT talking about your sync target (cloud), but a real backup ?
It could well be - the dev of the plugin may be able to help - that this brings up the needed list of broken links. OR ... the dev could release a new version (it is currently v1.2.3) which is able to do it ?
Just my 2ct

Joplin Batch Web provides tools for removing unused resources as well as checking for referenced resources that do not exist.

It's not a plugin but a webpage written by a contributor to this forum. It works in your browser using the Joplin API, not on their webserver.

However, if you are not happy with using their webpage you can download the files and host it on your own webserver.

When using any utility that can modify your Joplin data it is probably wise to make a backup first.