With release 4.6 OSM-Carto now much more strongly than before encourages you to map waterbodies and water covered areas of rivers (riverbank polygons) with multipolygons as large as possible. The established and documented practice of dividing riverbank polygons into small, easy-to-handle areas, maybe even exclusively with closed ways instead of more complex multipolygons as it is documented on the wiki, has now been declared undesirable by OSM-Carto.
Some might remember the multipolygon fixing efforts from earlier this year, the numbers are raising again and will be on the same level as before the fixing effort in 1-2 years. It is also well known that large multipolygons break more often and more likely stay broken than smaller ones. Yet incentivising merging of small polygons into larger ones as done by OSM-Carto has no influence on that of course, because ... oh look, over there, an ape with three heads...
And it is not that this problem is unexpected or no one has pointed it out before.
Hint for the wannabe map painters among you: If you have just painstakingly mapped thousands of small lakes in some area and loathe they are invisible on the map at all but the highest zoom levels just merge them into a giant multipolygon as well. Multipolygons with thousands of outer rings - no problem. And if the combined area is large enough you can make them show up this way - arbitrary thresholds nonwithstanding.
The work of the mappers: http://maps.imagico.de/#map=6/70.088/147.942&lang=en&r=osmlz&o=55&ui=8
What OSM-Carto shows of this: http://www.openstreetmap.org/#map=6/69.938/146.656
Is this still a map in sense of an attempt to visualize the actual geography?