This code from SERVER-74264 disabled constant folding for expressions involving $$NOW, $$CLUSTER_TIME, or $$USER_ROLES.  This prevents some relatively simple queries from being satisfied by an index.  For example:

db.coll.find({"$expr": {"$lt": ["$_ts",

]}})

will lead to a collection scan even if there is an index on the _ts field.

We should find a way to build an IXSCAN plan for such queries while still avoiding the plan cache bug fixed by SERVER-74264.

Note that this was inspired by HELP-52526 for a query generated by online archive.