In SERVER-110020 we documented some considerations that developers need to keep in mind when interacting with feature flags in the query system. I think it would be beneficial to apply those learnings and attempt to make some better helper functions or perhaps wrapper types around feature flags to ensure that it is very difficult to make the same mistakes going forward.

For instance, I think a common feature flag check is something like "is this new MQL allowed yet?" which is surprisingly complicated to get right.