update:
the latest OSM wiki discussion is 10yrs old (https://wiki.openstreetmap.org/wiki/Talk:Key:cycleway:buffer). These tags should probably be changed to cycleway:left=track (if vertical separation) or cycleway:left=lane (if no vertical sep) and then add cycleway:left:separation:?=? to describe the buffer type
research what OSM wiki says about this tag
update: the latest OSM wiki discussion is 10yrs old (https://wiki.openstreetmap.org/wiki/Talk:Key:cycleway:buffer). These tags should probably be changed to cycleway:left=track (if vertical separation) or cycleway:left=lane (if no vertical sep) and then add cycleway:left:separation:?=? to describe the buffer type