I hadn't heard about this before, so in case anyone else is also curious and wants to save some googling, it sounds like was a few months ago when they sponsored Hyprland[1]. I hadn't heard about controversy with Hyprland before, only being vaguely aware of it, but the forum thread I linked to further links to this blog post[2] with more details.
[1]: https://community.frame.work/t/framework-supporting-far-righ... [2]: https://drewdevault.com/2023/09/17/Hyprland-toxicity.html