Allison Garner

This could be a possibility too:

This one is more common in websites that are more than a few years old. Google has stopped obeying noindex rules in robots.txt files as of September 1, 2019.
If your robots.txt file was created before that date, or contains noindex instructions, you’re likely to see those pages indexed in Google’s search results.
The solution to this problem is to implement an alternative ‘noindex’ method.
One option is the robots meta tag, which you can add to the head of any web page you want to prevent Google from indexing.