I just started using Planetscale for small projects here and there. More and more of my projects are FE-heavy and don't require a big dedicated database (NextJS apps, mostly hardcoded designs or headless CMS like Sanity). There are times where I need to store just small bits of data, maybe contact form submissions or something. It's been super great to be able to quickly hook up planetscale to a nextjs api function and have that data persisted within a matter of minutes.

I've yet to use it on anything large-scale, though, so I can't speak to performance when you're really pushing it.