UPDATE: I found this issue explaining the relicensing of rust game engine Bevy to MIT + Apache 2.0 dual. Tldr: A lot of rust projects are MIT/Apache 2.0 so using those licenses is good for interoperability and upstreaming. MIT is known and trusted and had great success in projects like Godot.
ORIGINAL POST:
RedoxOS, uutils, zoxide, eza, ripgrep, fd, iced, orbtk,…
It really stands out considering that in FOSS software the GPL or at least the LGPL for toolkits is the most popular license
Most of the programs I listed are replacements for stuff we have in the Linux ecosystem, which are all licensed under the (L)GPL:
uutils, zoxide, eza, ripgrep, fd -> GNU coreutils (GPL)
iced, orbtk -> GTK, QT (LGPL)
RedoxOS -> Linux kernel, most desktop environments like GNOME, KDE etc. all licensed GPL as much as possible
GPL was the most popular at one point. MIT overtook it around the turn of the century, I think.