I am not talking about any “megapolygons”. I am just talking about the natural=coastline tagging. It is wrong. It’s not that the coastline is broken, it is in the wrong place. The coastline should be between land and the sea. The new coastline is not between land and sea, but clearly the land side includes huge areas that are now tagged as inland water when, in fact, they are clearly maritime water areas and were tagged that way until about a month ago. I am sorry, I didn’t comment on any changeset, but this comes up again and again and I have given up trying to figure out who did what and what changeset is involved. I just don’t have the time.

All I am saying is: The coastline processing is broken and somebody has to fix the data before the processing works again. Until then there are no coastline updates for the main OSM map and most other maps people create, because they depend on that processing.

I haven’t read your proposals, but we can’t change existing definitions of what a coastline is and isn’t any more anyway. This definition has been around for a very very long time in OSM and lots of people rely on it. Any new tagging schema can add additional information, but has to keep in place what’s already there.