Overlapping coastlines is not valid!
Coastline checkers (like mine) will detect it.
Since I cannot see the construction area on any imagery service (even not on Maxar Premium!) I cannot fix it.
So, it most likely is up to you to fix it...

(If not fixed) You will see the error tomorrow at noon UTC here:
https://tools.geofabrik.de/osmi/?view=coastline&lon=15.21785&lat=43.10634&zoom=3&baselayer=Geofabrik%20Standard&overlays=coastline%2Ccoastline_error_lines%2Cline_not_a_ring%2Cline_overlap%2Cline_invalid%2Cline_direction%2Cquestionable%2Ccoastline_error_points%2Cunconnected%2Cintersections%2Cnot_a_ring%2Cdouble_node%2Ctagged_node

Sorry...
Hat sich geklärt...
Ist ja in der Relation...

Okay, aber warum hast du Namen und Wikidata-Code gelöscht?
Ggf. auch den referenzierten Artikel bei Wikipedia als Attribut angeben...

Yes, I know, but it was not my changeset which destroyed the "heath" relation (#10901513). I just repaired the coastline part and removed a doubled way from that relation...
Since I am not a local I cannot say, how to fix this.
Putting the "heath" to the coastline way is wrong because it is not a closed line...

Hi!
Basically I think, you are right for way #4144152.
The problem is the enclosing way (e.g. way #554743433) which is also tagged as coastline which seems to be wrong.
Can you please also fix this?
Technically coastline may not defined inside coastline...
Greetings, Andre

Hi asibwene,
please, please, LEARN, that coastlines have very special rules!
If you continue to ignore them I will be forced to count your edits as vandalism!

Please learn, that for coastlines land must be always on left hand side.
See Wiki for more details.

Please do not add coastline tag to relations as it is only allowed for ways.
See WIKI: osm.wiki/Tag:natural%3Dcoastline

Please learn, that the coastline tag surrounds dry land! Read WIKI for more info. coastline is defined as the line of HIGH TIDE water. And wetland is flooded sometimes...

Please _never_ leave coastlines uncompleted! And please learn that coastlines are at high tide line! See osm.wiki/Coastline
Because of too much damage I now reverted this changeset. Please be more accurate next time...

Please finish your work as the coastline is now not okay. Each land area should get its own coastline. Also learn that coastline is high tide line! Read this: osm.wiki/Coastline

If this route is really disused than go ahead and mark it as disused... But marking it as coastline was definitely wrong and since the mapper was a newby this very much looked as a bad try.

Please learn that land MUST be on left hand side for coastlines.

Please don't remote the coastline tag unless you define a new one. Coastlines MUST be closed and there may be no gaps...

I did some technical fixes, but...
Are the new coastlines really "high water level"? See wiki: osm.wiki/Coastline

Why do you edit coastlines while you don't know how...?

First of all coastline MUST be a closed line and thus you either have to leave it as is or to tag the whole river as coastline which is much more complex since you have to both edit the river relation _and_ to add coastline tag to islands... Hence it is common use of tagging the coastline at the border between river and sea/ocean.
You are free to remove the coastline tag again _IF_ you add the coastline tag to the whole river... have fun...

Hi Gescriey,
just for your information. The coastline update process has stopped because of a bigger edit at antarctica. I've informed the talk-list and hope that someone will take care of it...
You can follow the discussion here: https://lists.openstreetmap.org/pipermail/talk/2022-January/087193.html

Hi Gescriey,
it's because coastline tags are not allowed for relations. They are on the enclosing way of the islands itself, which is correct.
The reason, why it is (yet) not rendered correctly is that the tag was added at 24th and these changes may take several days to appear on the map. So my advice would be to simply wait a few more days...

I simply don't know a better way of tagging this correctly. The problem is, that both bare_rock and coastline use the natural key. And the only way of using this both is a MP. Since this existing island was not visible on the map, I added the coastline. As coastline must be tagged on the way, the bare_rock goes to the MP. If you know a better way, please let me know.