Hi y'all! This is Kai from the Cider Discord server,
I'm not sure of this behaviour for previous Cider versions, but with Cider 2.3.0, the default limit for songs able to be queued is actually 100. This means that any playlist with over 100 songs will not shuffle all the songs. However, you are able to set that limit to any amount, including no limit, if you set the number to 0. This, however, may come with some performance issues, so make sure to keep that in mind when changing the value.
This setting can be found in Settings > Advanced > Library Queue Limit (Set to 0 for no limit)