It looks to me as if there is both a round hole and a triangular hole, but one would have to see the fork first hand to verify. Perhaps I'm misinterpreting a scratch or dirt. A round hole is normal construction, but I don't think a wedge shaped hole is. Nonetheless, the construction on the fork should be roughly symmetrical, so one can inspect both sides to verify construction technique.

If the dropout is stable, then it probably isn't an issue, but still looks odd.

The dropout itself should not move. One can grip it with pliers and try to move it if one wishes.

That really deep wear is definitely not normal for a steel fork. There are road bikes that have been ridden for tens of thousands of miles, perhaps even hundreds of thousands of miles without wear like that, some with dropouts made of softer materials.