Fujifilm is probably one of my favorite companies right now. They produce some of the best products within their respective formats. For APS-C the X-T series of cameras are probably the best. For medium format, the GFX 100 is the best in several key categories. Unfortunately, the problem I and many other Fuji shooters face, is the unreliable autofocus.
Phillip Bloom recently uploaded a video, demonstrating and discussing the video autofocus limitations of the the Fujifilm X-T4. As good as this camera is when it comes to its stills performance, Fuji has been making a concerted effort to improve its video features. On paper, the X-T4 seems like the perfect aps-c camera for video; features like IBIS, log profiles, and resolution are brilliant. The main problem however, is that the autofocus still isn't quite up to par.
This could primarily be down to the fact that the lenses themselves are not designed for video. This also makes this a difficult fix, because many of the popular focal lengths would need to be updated in order to correct this. For example, the Fuji 56mm f/1.2 is an absolutely brilliant lens. The kind of images it can produce are beautiful. Unfortunately, it's pretty difficult to use for video if you're trying to shoot with autofocus.
In the video above, Bloom goes through many of the Fuji lenses and discusses some of the things you could do to correct a few of the problems. Unfortunately, the underlining issue may take Fujifilm a while to fix.