Open-source, and technology in general. There was a time when I would spend most of my free time playing with niche software, learning about the history of free software movement and trying to get into programming.

Nowadays? Well, I still use and love free software of course. I wasn't disillusioned in it or anything (especially given the state of modern proprietary software, eg Windows 11). But the interest is gone - I have my comfy setup, and changing or fixing anything in it feels like pain. I can't stand drama that fills the open source community and prefer to keep VERY, very far from it. Outside of gamedev, programming didn't work for me that much (as a hobby - I do want to make money off it).

My interest in Fediverse is an accelerated version of this due to the social aspect of this technology - after trying out the microblogging part of Fedi I realized that social media isn't for me, and so only Lemmy remains in my daily usage.
To be fair, I don't use the centralized services which the Fedi projects are meant to replace (xitter, instagram, youtube, etc).