Still? It is the best and the most mature cross-platform toolkit. Among both open-source and proprietary ones. It is the default for embedded / industrial UIs and automotive. At least in Europe but I think many US companies like Autodesk also use Qt. Its programming paradigms are a bit outdated. However, it is quite performant and supports many 2D and 3D acceleration drivers / APIs.

I'm not sure I agree the paradigms are outdated. Sometimes the new stuff ends up worse for the problem

Qt pretty much owns the automotive market.

Medical also