Looks like a boundary between tiles there: https://maps.wikimedia.org/osm-intl/4/2/6.png https://maps.wikimedia.org/osm-intl/4/2/6.png https://maps.wikimedia.

Looks like a boundary between tiles there: https://maps.wikimedia.org/osm-intl/4/2/6.png https://maps.wikimedia.org/osm-intl/4/2/6.png https://maps.wikimedia.org/osm-intl/4/3/6.png https://maps.wikimedia.org/osm-intl/4/3/6.png Placing labels on a map is quite a hard problem, especially when certain tiles are refreshed.