Wordpress broken internal links

My website is around 14 years old and I'm in need of someone to fix broken internal links, for example this page
https://www.seolady.co.uk/2008-to-today/

All of the links are missing a '/' forward slash, they all follow the same broken format, example:
https://www.seolady.co.ukseo-rankings-google-website-redesign-domain/
https://www.seolady.co.ukvideo-and-seo/
etc

I've always made sure internal linking is an integral part of my blog posts and pages, I feel a theme swap in 2020 may be the culprit.

Perhaps there is a tool or script to identify all broken links?

Please begin your bid with "Allow me to explain like you are 8 years old" so I can understand what you need from me.

Copy and paste bids will be rejected