[{"_id":ObjectId("63920f965d15e98e3d7c450c"),"owner":"yyy@hotmail.com","products":[{"name":"name","pid":41,"qty":3},{"name":"name2","pid":42,"qty":4}]}]

db.collection.update({products:{$elemMatch:{pid:41}}},{$set:{"products.$[item].qty":19}},{arrayFilters:[{"item.pid":41}]})