Feed querystring not working as expected (or maybe how it used to pre 3.5?)

I’ve been using RSS feeds with querystrings in them to pull specific content from sites.

This is an example I set up: https://demo.jarrodpyper.com/feed/?post_type=syndicated&category_name=craft

This shows two posts, one titled “test syndicate” and the other “post”

The goal with the querystring is to only grab content in the custom post type “syndicated” and of the “craft” category. I think that it used to work fine, but I’ve just noticed that it’s not now.

In my example, “test syndicate” is in my “syndicated” post type but “post” is a regular post. “post” should not be showing given the querystring. Right?

If I’m wrong, why am I wrong? I scanned trac for 3.5 and didn’t see anything directly related to this.