See Error 403 when using local files - referer missing - can I use User Agent and what should it contain if it is a local file
See Access blocked on osm.org if you see it on osm.org
If you see it somewhere else it is site in violation of Tile Usage Policy or you use weird browser extensions/weird browser/other weird setup.
for start, it is using wrong url and violates tile usage policy, see Tile Usage Policy
You must:
- Use the correct URL:
https://tile.openstreetmap.org/{z}/{x}/{y}.png.