Are you in the markdown editor or the viewer? IIRC, markdown links have never been followable in the markdown editor on android (only in the reading view)...
There is a change in the mobile version where it no longer always defaults to the reading view when accessing a note, it now defaults to whatever you last used (editing view or reading view). Could that be the behavior you're referring to?
EDIT: If you are referring to the editor, if you had disabled the render markup setting per the troubleshooting suggestion from this thread: Links to YouTube videos disappeared - #3 by mrjo118
That would explain why bold is showing as **bold**, if you want it to show as bold in the editor you'd need that setting enabled.