I have fixed the coastline of Cửa Lò Township in Vietnam, but this occurred:
Can a person fix this?
Thank you,
Tuấn.
HI and welcome to OSM and the forum
Please note that coastline rendering is diffrent from rendernig normal features: https://wiki.openstreetmap.org/wiki/Coastline#Rendering_in_Standard_tile_layer_on_openstreetmap.org