Please read this article from user perspective (I do not personally know the author): https://serpapi.com/blog/how-a-routine-gem-update-ended-up-charging/

And the comments on HackerNews: https://news.ycombinator.com/item?id=29845724

It is important for the Mongoid team to understand the consequences of making changes like these in the real-world. I was personally against this "or" change at the time it was done (chaining .or().and() makes the API very counter intuitive), but I guess it was done to be compatible with Rails. The comments on HN are correct that it should have been a major version bump according to Semver.

I would recommend the team look at MONGOID-5172 as a way forward.