Grammarly is one of those services with an obscene base price and fat discounts available, though. I’ve been getting it for $60-70 a year for a while now via 50+% off Black Friday/Cyber Monday deals.

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.