The pricing is not that bad given Grammarly is $12 / month and is getting progressively worse every month. If Fixkey had a Windows version, I'd give it a try.
They also have AI-based functionality along with traditional correction. Their correction works pretty well for me, but their client software blows and hasn’t gotten better with time, to your point.
OTOH, my employer has vetted and allows Grammarly but doesn’t allow random AI-based products or OpenAI API utilities that take my own key, for security reasons. I suspect a lot of others who actually would need to use a grammar checker professionally might be in a similar position.
Have you noticed any degradation of traditional corrections? Recently, Grammarly started correcting its own earlier corrections in, if I allowed it, an infinite loop.
FWIW, a few years ago Google didn't allow Grammarly; I don't know the current status.
I don't want to come across as too negative about Grammarly; it is useful and has an enormous potential. I hope the company finds its way.