Congratulations on your new job! It's very common for many people in full time "knowledge work" positions to only spend 4-5 hours on "real work" and to feel self-conscious about that. Especially with everything going on in the world, that's a completely reasonable amount of effort to expect from anyone.
Good to know! Since i'm expected to manage my own schedule, and I can do a lot of the work at home - the issue becomes the amount of hours I "count" as work-related. Because If it were a regular 9-5 job, the 20 minutes spent making coffee or talking to a coworker counts as working hours. I have friends who spend their "work-time" planning their next vacation (admittedly they work for the government). But if I only count the hours I'm TRULY working, 30h/week can become a lot quickly. Hopefully I'll have some long mindless stuff to fill the time a little.