If it works for you that’s great. Every one I’ve experienced is so high up that it is literally a pain in the neck.
I suspect a minority of TVs over fireplaces are rarely used, or just used for utility (news, etc). Those ones are usually the worst ones where you question the sanity of placing it there.
Also, after pondering it more, I also suspect really large TVs up higher with a father back seating position are less of an issue. If you visualize that, the angle of looking up gets shallower the farther back you go.
The cliche of TVs over fireplaces being bad starts with smaller tvs many years ago. I suspect your situation is a reasonable distance back. And your tv is big enough to support that distance.