No, Stranger Things season 4 has 9 episodes, not 4. Season 4 was released in two parts: Volume 1 has 7 episodes and Volume 2 has 2 episodes, for a total of 9. If you are only seeing 4 episodes on Netflix, it may be showing you just a portion (for example, a new season like season 5 releasing in smaller batches), your profile’s “Continue watching” row, or a regional/parental restriction.