Hello Mikael888,
Thank you for using Apple Support Communities. Based on your post, when watching 'For All Mankind' on the Apple TV app, the age or rating doesn't disappear as expected.
When we playback Season 2 'For all Mankind' on a Mac with Monterey, the age requirement is reflected as 'MA' for Mature. With that said, it does disappear after about 5 seconds into the each episode. This may only be happening with your device and/or app. Let's discuss it further.
Which device are you using to play season 2? Does this occur on all of your Apple devices?
Have you noticed this behavior in any other show on the Apple TV app?
Do you have any restrictions set up on this device? See: Restrict access to content in the Apple TV app and Parental controls for Apple TV+ on the web
Hoping to hear back, take care.