The header above a path used to stop at the path's name. It now spells out where you are: on the roadmap it reads Paths, the path, then the tab (Roadmap, Recommended projects, Interview prep or Certificate); on a chapter it reads Paths, the path, the layer (Foundational, Core Skills or Advanced Skills) and the chapter you are reading. Every crumb before the last one opens the roadmap.
On a chapter, the Back to roadmap link changed the address but left the chapter on screen. A chapter and its roadmap share one address and differ only in the part after the hash, and the page was not told when only that part changed. The link now switches the view the same way the roadmap tabs do and always opens the Roadmap tab, whatever tab you came from. The same fix applies to Back to the roadmap on a chapter that is still being prepared.