Relatively simple rewrite rule not effective

I want to have requests to this url result in a 404 response, via the Rewrite Rules setting for the virtual host in the OLS web console:

I have a 404 rule working for another page, but this one has been stubborn to find the right rule expression.
I've tried this, which doesn't work (the page loads normally), as well as easily 50 variations of it while reading through documentation:
RewriteRule ^/\?cat=-1 - [R=404]

Debug logs are not giving me any feedback.
Any suggestions that could save my sanity?
Thank you.
Never mind, I figured it out!
This is one way to fix the Google Search Console breadcrumb issue in Wordpress.
Here's what worked:

RewriteCond %{QUERY_STRING} ^cat=-1$ [NC]
RewriteRule ^ - [R=404]