bxl-forever
Hello,

Access tags are are more elaborate feature of OSM.
This path has "access=no" indeed, but it also has "foot=yes" and "bicycle=yes".  This is a standard tagging practice.
Routing engines should treat tags in that order.  In everyday language that is the same as saying: "This path is not accessible… except for pedestrians and cyclists."

https://www.openstreetmap.org/way/277739778

The path looks correct to me, i.e. accessible to pedestrians and cyclists, barred to motor vehicles, and surface=cobblestone + smoothness=very_horrible ;-)