I discovered that after all these years, I've been putting the cabin air filter in the wrong way. Say what you will about K&N, but I accidentally ran across their video and they set me straight. After all these years, I never knew that I was supposed to roll the front 1/3 of the filter back under the filter frame.
https://www.knfilters.com/video/vf3001_install.html
https://www.knfilters.com/video/vf3001_install.html