More details on why this was wrong would be very helpful.

After reading the wiki i believe this would count as a beach.

Ah okay, well yes I still believe it counts as a beach based on what you linked.

But i was mistaken, it would also have Gravel and some pebbles in it.

Still not sure why this has been alerted.

I based it of this. https://education.nationalgeographic.org/resource/beach/ and https://en.wikipedia.org/wiki/Beach which says lakes can have beaches.

Live in the area and can see it's sand. Feel free to remove if this is wrong.