We see things similar to this in the USA. Our US Bike Networks “What to Map” (and NOT to map) wiki might be helpful, as it’s an easy thing to point to which quickly became liked by many and has never been disputed (and so “sticks by osmosis” or something like that). UK (Canada, Australia, wherever…) is welcome to grab the text and use as is or modify to local liking.
Armed with this, you can redact such drek “with authority.” The bottom line is, “OSM doesn’t map what is simply ‘a good ride,’ as these can be far too subjective or ephemeral” (and there are other sites which do this, often using OSM data as their base map!) A PROPER bicycle route is published by a government or signs-on-the-ground (or if proposed, is about to).