Only people who have your link (and, in Race ID + access code mode, the code). Races are never listed publicly.
Followers see: the map with the whole route and your position, your distance, pace and finish prediction, your phone battery (unless hidden) and the viewer count.
Cheers are private: a cheer's recording or text is only for you (and its sender). Other followers only see who cheered and when.
The recap is only for you (and the other runners of a group race).
You see your followers: the names they typed, when they watched, their cheers and claps. You can block a follower.
To cut off everyone who has the old link, reset the access code in Race settings. That cancels every link shared so far.