Repro:

execute mongod
$ build/debug/install/bin/mongod --setParameter featureFlagSBEGroupPushdown=true --setParameter internalQueryEnableSlotBasedExecutionEngine=true

in MongoDB shell
var coll = db.getCollection("test");
coll.insert({a: 1});
coll.aggregate([{$match: {$or: [{"a": 1}, {"b": 10}]}}, {$group: {_id: "$a"}}]);

In SERVER-60191, we disabled $group pushdown to SBE when $match stage with $or exists in a pipeline to avoid a tripwire assertion: 5842500. This assertion happened because subplanning does not expect that the base query has pushed down $group stage(s) and it does when $group stage exists in pipeline. But two code paths are orthogonal to each other.

Need to figure out how to enable $group pushdown to SBE even when subplanning is involved.