Jellyfin certainly does have double speed and playback speed settings. I know this because I used it today. However it is the first time I noticed it there
https://fountain.fm/episode/T3F8BiaU3EkUYFAjRVoq
nostr:nevent1qvzqqqpxquqzpw7qr74t5tddpt2y56s0zeng6x6nn06x7l4heqtez5k6fg5ssw2k0yxvzq