A few things that I notice in the area where I'm somewhat active as an OSM contributor:
- You probably shouldn't render guideposts or route markers on the map, or at least not with generic "info" icon.
- Things with access=private are likely not terribly relevant to people looking at the map. This will include things like parking spots or gardens.
- Lots of shots and amenities have icons, but doctors don't. Neither do fire stations.
- Sports pitches are shown as nodes, but may be better shown as areas, since they often cover quite extensive swaths of ground that's otherwise empty with just an icon in the middle. Same with playgrounds, schools, and kindergartens, gardens, and parks.
- For buildings and building parts, if you don't make use of the parts in any way (such as showing roofs, height, etc.) perhaps just disregard the parts and only render the building outlines. This, combined with the fact that geometries seem to be simplified, even at the highest zoom levels, results in a bit of a mess of lines at times where some outlines are simplified differently from others that should actually share parts of the same edges and thus overlap perfectly. (e.g. https://maps.earth/place/openstreetmap%3Avenue%3Away%2F11120... or https://maps.earth/place/openstreetmap%3Avenue%3Away%2F11120...). Same thing with the geometry simplification also happens with adjacent geometry that should actually not have gaps (e.g. semidetached houses or garages next to houses). Lots of buildings that are actually rectangular also get quite weird angles.
- Tunnels are quite subtle. And while at least roads in tunnels don't overlap buildings that are actually above them (like with Carto) it's still hard to make out what's above and what's below in such cases (e.g. https://maps.earth/place/openstreetmap%3Astreet%3Apolyline%3...). Culverts for waterways are handled better than roads in tunnels in this case.
Overall though, this seems like a quite nice map style. Closer to Google Maps in that it emphasizes roads, but some people like the less detailed look (and it works better with vector maps, I guess, to have fewer polygons to render).