Netflix works differently than most other networks/outlets. A viewership drop is expected in most places, before viewership hits a plateau, and that’s where your steady, loyal viewers keep you afloat. For broadcast networks, if you have a solid enough loyal viewership that advertisers can depend on to show up, you’re good. For Netflix however, they are notorious for cancelling shows once they stop bringing in new subscribers. Which is why there are barely any Netflix shows that get to finish their planned runs. Season 2 is usually their shows’ breakout season - where they peak. Because enough viewers caught up on S1 that they built up quite a buzz for the return season. Then the shows kinda level out and start losing viewers from season to season and face cancellation. That was not the case for the Witcher. The buzz from S1 simply did not give them that usual sophomore season boost, which puts them in that usual cancellation danger a little earlier than their other hit shows.