There may be some ambiguity here (naming things is hard). The example you shared is the $min aggregation operator, whereas what’s been deprecated is the $min query modifier.

For example, you can still do the following in 6.0+:

db.sales.aggregate(
   [
     {
       $group:
         {
           _id: "$item",
           minQuantity: { $min: "$quantity" }
         }
     }
   ]
)

however you would no longer be able to do:

db.sales.find({ $query: {}, $min: { quantity: 25 } });

but would instead need to use the cursor methods such as:

db.sales.find({}).min({ quantity: 25 });