But now, I think that C++ is more of a drawback than an advantage for the Qt project. C++ today seems a good fit for high-performance, very niche tools such as trading, games, machine learning libraries, and such, but not for "simpler" software such as the UI of an application. Also finding good competent C++ devs seems to be much harder now. I myself feel like having to go "back" to writing C++ is a bummer, having worked with other more modern technologies.
Bindings to other languages have always been a second-class citizen. The Python one is very nice, though, but that's all. I believe it comes, again, as a difficulty introduced by the language itself.
Even with all of that, you generally end up reading the C++ docs, it isn't particularly Pythonic, and there are weird gotchas. I can't really fault them for it because you're bound to get that with bindings to another language and it is much better than other UI toolkits.
Even then, the total addressable market was pretty small, but at least it was anyone who wanted to make a cross-platform app.
Now, most people who want to do that use Electron, React Native, or make a browser extension (or, of course, a Web site). The market is smaller: cross-platform makers who are absolutely committed to Qt or for whom it’s a uniquely good fit (like because they’re using C++).
Think of it like a pharma company with a drug that only treats a rare disease. The TAM is tiny. Unless someone discovers that it also treats some other disease, there’s not a lot they can do to expand the customer base. If they want to make more money or want more short-term revenue (usually at the expense of long-term revenue), charging existing customers more may actually be the best option for them.