2

I can’t see any issues with the mapping it looks fine. JOSM validate has no issues, and http://tools.geofabrik.de/osmi/?view=coastline also doesn’t report anything.

In the history of https://www.openstreetmap.org/way/484623696/history the way it was tagged was changed Oct 2019 and then changed back in Feb 2020, https://osmdata.openstreetmap.de/data/land-polygons.html was updated in Janurary. It’s not clear to me from https://wiki.openstreetmap.org/wiki/Coastline#Rendering_in_Standard_tile_layer_on_openstreetmap.org if the standard tile layer is relying on the land-polygons data from January at this zoom level, but it’s possible.