Split Bus?

If so more that 6 throws, don’t usually see main breaker in middle of panel.

It appears to be. But with the single pole breakers in the top half, there are more than six handles to disconnect all power.

Looks like it is a split bus, but maybe rearranged. I would have it checked out.

The breaker that fed the bottom bus was commonly labeled main or lighting main. The other breakers were labeled like stove, a/c, water heater etc.

That is clearly a split bus panel. Checking the label would have confirmed this.