How to stop google from indexing spammed internal search results?

Google is indexing all kinds of spammed internal search results from my wordpress site, and I can't figure out how to put a stop to it. I added Disallow: /search/ to my robots.txt file, but that didn't stop google. They still index them, but now they say Indexed, though blocked by robots.txt

What can I do to stop these from being indexed? And how do they even show up for google? Is there somewhere within wordpress that these are being stored that google is picking them up from?

Any help would be much appreciated!

Here's what I see in google search console: