Yes I agree the timeline should be defaulted to off as certainly the MotoGP use of the timeline does seem to give immediate spoilers (overtakes/crashes/penalties). There also seems to be a different (inconsistent) approach in how the timeline works between sports. Eg if I replayed yesterdays Football I only get the timeline events that have occured upto the point I have watched whereas the MotoGP gives all at the start.
Probably worth mentioning that timeline markers are I believe available on some programming on specific devices rather than across the board although I believe Discovery+ have been expanding its availability.
It’s most frustrating when watching Moto GP later on. If you want to fast forward to the race start you need to go up to the scroll bar to get to the race start icon. But for some reason they have decided that the “cursor” starts at the far right so you then have to go left across the bar seeing every event of the race before you can get to the start icon.
An utterly rubbish poorly thought out and delivered design.