S0508: Chapter Eight: The Rightside Up was aired on January 01, 2026. It's had mixed reception though, with many fans expressing disappointment over supposed poor writing that left many key plot points unresolved.
Multiple theories (eg. Conformity Gate) have emerged from the fandom proposing that the episode was not the "true" series finale, that it was somehow made intentionally misleading by the showrunners, and that the the "true" ending will be revealed in the near future (potentially on January 7th, making this a short fuse market if so).
https://x.com/SThingsMeme/status/2008149159912816938
https://x.com/WilloMCI/status/2008159311139074390
https://www.tiktok.com/t/ZP8ywrRuJ/
(I might add new answers later, maybe.)
1,000FYI there's a related Kalshi market: https://kalshi.com/markets/kxmediareleasest/will-there-be-another-episode-of-stranger-things/kxmediareleasest-27jan01