I found an important note (probably related to this bug) which indicates following information:
On Cisco Nexus 9300-EX, -FX, -FX2, and -GX switches, when 802.1q EtherType has changed on an interface, the EtherType of all interfaces on the same slice will be changed to the configured value. This change is not persistent after a reload of the switch and will revert to the EtherType value of the last port on the slice.
source : https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/interfaces/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_Interfaces_Configuration_Guide_7x/b_Cisco_Nexus_9000_Series_NX-OS_Interfaces_Configuration_Guide_7x_chapter_0110...
If we change the ethertype value on a port between 1 to 48, configured valued is applied to all port 1 to 48 or to all switch ports (1 to 54) ?