Some time since January, the rendering of lakes, ponds etc. on Garming GPS devices has apparently failed for the United Kingdom. Lakes in the United Kingdom are no longer shown in blue. I posted a question on the OSM help forum (https://help.openstreetmap.org/questions/49058/rendering-of-lakes-on-garmin-devices), and the expert replies that I received seem to point to a recently created polygon enclosing Great Britain as a likely cause. Is there anything that can be done with the downloaded maps to avoid this problem, or is a change to the OSM data the only possible remedy?
I regret that my understanding of map rendering falls rather short of ‘expert’, but it appears that, where two types of land use apply to a given region, Garmin devices can choose either one of them, whereas the rendering on http://www.openstreetmap.org is possibly aware that, where one land use polygon completely encloses another, the inner polygon should define the rendering.
If asking about some other pre-made maps, you’d want to ask whoever it is who makes them.
If you were making your own Garmin maps (and I know from https://help.openstreetmap.org/questions/49058/rendering-of-lakes-on-garmin-devices that you’ve said that you aren’t) it might be possible to work around the problem. Interestingly, on my own Garmin maps (the creation of which hasn’t changed for about 5 years!) I do see Lake Windermere in blue, but it does appear to be called “Great Britain”, as does other landuse nearby. Near York howeever, that problem doesn’t occur - the local landuse areas have the correct name.
There’s a mailing list associated with the most popular software used to create Garmin maps over at http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev - that’s where people are most likely to know how to fix it, but following any answer there would involve making your own maps, which is an order of magnitude more complicated than what you’re doing now.
This need to be fixed in the tools that create the Garmin maps, not in the OSM map itself. Requiring local exceptions to land use to not overlap the larger scale use would result in an excessive use of relations, which are inefficient to process and difficult for newcomers to edit properly.