Indexed Pages Different when I perform a "site:Google.com" site search - why?

[accpar]

My client has an ecommerce website with approx. 300,000 URLs (a lot of these are parameters blocked by the spiders thru meta robots tag). There are 9,000 "true" URLs being submitted to Google Search Console, Google says they are indexing 8,000 of them.

Here's the weird part - When I do a "site:website" function search in Google, it says Google is indexing 2.2 million pages on the URL, but I am unable to view past page 14 of the SERPs. It just stops showing results and I don't even get a "the next results are duplicate results" message."

What is happening? Why does Google say they are indexing 2.2 million URLs, but then won't show me more than 140 pages they are indexing?

Thank you so much for your help, I tried looking for the answer and I know this is the best place to ask!