You can try my Lemmy app, Arctic. It’s a pure swift based iOS app, written with performance, and content presentation in mind. It’s packed full of features, and new ones are being added constantly.
You can read more about Arctic over at !arctic@lemmy.world
This is most likely the preferred language setting on your account. By default, it’s set to unspecified. If you change it, then everything with a different, or unspecified language is filtered out. Since the majority of content on lemmy has an unspecified language, you’d be missing out on most content.