the_author_posts_link()

The code actually reads:

This article written by <?php the_author_posts_link(); ?>

The link it attempts is https://www.improvethequality.com/author/jason/ but it then goes to the front page.

See if updating your permalink structure resolves the problem.

I tried it with the default and it didn’t help. Do suggest a particular structure?

Not necessarily another structure, but do “Saving Changes” with your existing default structure. Note that with the default structure I would expect your link to be something like:
https://www.improvethequality.com/?author=1

When I changed it to the default the link was “https://www.improvethequality.com/?author=2&#8221; but the same result of going back to the home page in stead of an author page.

I put it back to my custom structure after that and saved again. So, it is back to the way it started.

Guessing either something in your .htaccess or a conflict from a plugin (or theme).

That is what I thought as well, I have deactivated all the plugins I thought could affect it one at a time. The theme works on my dev site. In fact this whole thing works on my local dev site. (it isn’t a perfect copy of my real site) I just can’t find out the difference.

I will look into the .htaccess file.

It turned out to be the Robots meta Plugin.

I wouldn’t have guessed that one.