I checked out Slint and immediately closed out when I saw a pricing page. Some software is worth paying for, but a GUI library for me isn't one of them. A community can usually keep a GUI library going because it doesn't change a lot after it matures.
Yeah, I'm not going to verify all the maintainers of the software I use is vegan, believes in climate change, and left. While I believe the causes are just and important, not every moment is a time to align values and divide.
I've enjoyed ProtonMail quite a bit the last year.