I haven't looked at MobX in a few years, but last time I looked at it it was just wrappers around state that people were encouraged to mutate directly. And I don't quite see how there could be MobX hooks (I assume there are some at this point) that have methods exposed that aren't called from within components.

The thing I like about RTK query is that, even though Redux is now heavily weighted toward hooks, those hooks give you a whole lot of power for anything related to API calls--state related to fetching and ways to call the query again manually if you need to are all wrapped up in a neat little bundle. You then have to figure out ways to keep that separate yourself, if you want to, but it's very powerful.