Like many in the thread, I also had this experience of going all-in on podcasts during my passive time, and then after a couple of years realizing that I had stopped doing any thinking of my own.

For me personally, podcasts are great while grocery shopping, washing clothes or other chores that engage me too little to be interesting, but too much to let my mind wander into critical thinking mode. I'm sure this threshold is different for different people.

But for intentionally passive time, like walking or running, I've stopped listening to podcasts. I may or may not listen to music.

Especially for running, I'll intentionally choose a topic beforehand to think about, and then actively think about that topic. I've found that extremely stimulating.