The list of problems goes on, but if you want really current at a local presentation a few weeks ago a user who's actually pretty positive about MongoDB reported data loss without hardware failure with what is supposedly a safe configuration. If even experienced people who like Mongo are still losing data eight years after publich release there's a problem. The claim that it's "not true for many years now" is the result of buying into PR and fanboyism.

Again the same old accusations without a single source ('local presentation', of course!).

February 2017: https://jepsen.io/analyses/mongodb-3-4-0-rc3

I would expect these bugs to keep occurring, because they're still approaching the development of the consensus algorithm incorrectly. Instead of formally proving correctness, they're doing something that seems right and then patching bugs when they are discovered.