I noticed that the Zabbix Agent uses different key values for the same Memory utilization item on Linux and Windows hosts.

The "Windows by Zabbix agent/active" template offers the "Memory utilization" item with the key vm.memory.util.
This is a calculated item derived from the vm.memory.size[used] item.

The "Linux by Zabbix agent/active" template also offers the "Memory utilization" item with the key vm.memory.utilization.
This one is a dependent item from the vm.memory.size[pavailable] master item.

Note that these items have the same name and purpose, but with different keys.

Although Linux and Windows hosts have different methods of capturing memory data, the data is mostly the same after it reaches Zabbix.

Having different item keys causes some differences in dashboards and makes switching between Linux and Windows hosts unavailable.

For example:

A dashboard widget displaying memory utilization for hosts selected by the dashboard host selection can only display one type of host: Linux or Windows.

If the widget is configured with a Linux item, Windows hosts won't be shown, and vice versa.

Linux host:

 
Windows host:

Therefore, the "Memory Utilization" item with a key mismatch prevents widgets from different operating systems from being displayed.

I suggest matching both keys from the Linux and Windows templates.
This will allow for more flexible dashboards and possibly new aggregated calculations.