I don't think this is just an issue of the murky convention around flexposts actually. Consider ways like this one, where the paint only (and in many places advisory only) bike lane is mapped as a cycle path https://www.openstreetmap.org/way/1288106328

This isn't a data problem only for tools, or tools and the renderer. I as someone manually inspecting the map had to look for other imagery and look for project details to see if this was just out of date imagery. It's not, there hasn't been a major road project in that location since the 2023 orthos. 