How does cycle tracking work, and who can see it?

It is off unless you turn it on, it has its own separate consent, and you control who sees it.

Cycle data is health data under POPIA, so it is treated differently from the rest of the app rather than being folded in with it.

It is off until you turn it on
Nothing is collected, and nothing appears, unless you opt in.
Read the consent screen properly
It has its own consent, separate from the general one you gave when you signed up. That is the point of it being separate: agreeing to use the app is not agreeing to this.
Log what you want to log
Once on, it appears alongside your training so you can see the two together.
Turn it off whenever you want
Withdrawing consent is as available as giving it.

Worth knowing

Your coach does not see this unless you have chosen to share it.
Deleting your account deletes this with everything else, and you can do that yourself from Profile.