Hello,
I have been using the plugin for many years on sites, continued with the local checker and it has performed very well.
On one site, WordPress ver 6.4.3, PHP 8.0, no recent changes made to the content on the pages. It uses <a href="#">Back to top</a> at various places on most pages and on a Glossary page, it uses <a href="#a">A</a> for each of the 26 letters of the alphabet to take to entries under each letter.
Opening today, I found that Back to top has a strikethrough and each letter of the alphabet at the top of the Glossary page also has a strikethrough. All of the links still work.
Going to the Broken Link Checker page, I found a total of 77 broken links listed, all reporting 503 Service Unavailable. I dismissed the broken links and ran the checker and so far none have reappeared. I would appreciate some advice on how, or why this may have occurred.