How to group by and count with mongodb?
According to the mongo manual on $group, the command should be like this.

db.requests.aggregate(
    [
        {$match: {         
                "updatedAt" : {"$gt" : ISODate("2020-05-14")},
                "status" : "SUGGESTED" 
        }},
        {$group: {
            _id: {updatedBy: "$updatedBy.displayName"}, 
            number: {$sum: 1}
        }}
    ]
)