As far as I'm informed, you can have live streams uploaded to Twitch for a maximum of 60 days, after which they should be deleted.
But I noticed that there are still a few videos that can be accessed on many channels, some of which are 2 to 5 years old.
The time in between is missing again. Can someone explain how this works on Twitch?
These streams are usually uploaded as highlights. If you give me examples I can explain this to you in more detail. Highlight videos are not deleted from twitch unless there's content that is prohibited on twich. The normal videos are either deleted after 2 weeks (not partner) or after 60 days. In addition, the streamer can always decide whether the streams are to be saved at all.