What icon theme is that on the Pinephone?

It’s Papirus.

Is this the offline translator in Firefox?

No, it’s a standalone app for online translation.

Can’t they change this status?

Thanks! I enjoy this platform.

The only thing that is missing from Reddit for me is a mobile-friendly app for GNU/Linux (I used Headlines for Reddit). But browser version is so great, I use it from the phone with no issues.