I read the series as far as it went back then when I was a teen and even then I oupd notice the quality diving deeper and deeper with each book

It’s not.

David Talbot isn’t introduced until Queen of the Damned

Also, The Vampire Lestat starts out in France in the 1700s.

In the winter of my twenty-first year, I went out alone on horseback to kill a pack of wolves.

This was on my father’s land in the Auvergne in France, and these were the last decades before the French Revolution.