Hi, trigpoint!

Here is the documentation for the project you are writing about - https://wiki.openstreetmap.org/wiki/Organised_Editing/Activities/missing_roundabouts_UK
and - https://github.com/mapbox/mapping/issues/420

There is a footnote on the osm wiki page about turn restrictions - https://wiki.openstreetmap.org/wiki/Relation:restriction - "Some mapping companies are adding unsigned implicit (unsigned) restrictions - https://labs.mapbox.com/mapping /mapping-for-navigation/implicit-restrictions/"

Here is the link where we notified the community - https://lists.openstreetmap.org/pipermail/talk-gb/2023-February/030053.html

If you have any questions feel free to ask me.
Have a good day!