In few scenarios, a single serial number is used for the same product but with more than 1 item.

In some scenarios, it is needed to sell 50 units of each item in a single transaction at the POS.

However, this requires excessive scanning, which is not ideal for a retail environment.

As per "Work with serialized items in the POS - Commerce | Dynamics 365 | Microsoft Learn" document:

“When selling or fulfilling serialized products through the POS application, a quantity of "1" is enforced for the serialized items on the sales transaction. This is a result of how the serial number information is tracked on the sales line. When selling or fulfilling a transaction for multiple serialized items through POS, each sales line must be only configured with a quantity of "1".”.

This is a feature request to have a feature to allow customers to increase the quantity of serialized items in the POS cart if the feature is enabled.