I have recently hit a vlan scale limitation FEX N2K-C2348TQ-10GE,which has caused some weird anomalies;
1. by using switchport trunk add vlan "X" on a host interface, it deleted all vlan configuration on that interface and applied the config of the next interface.
2. Cant add anymore vlans on the host interface by using "switchport trunk add vlan".
I have found a documentation saying that there is a scale limit of 75 vlans for a host interface, but it doesnt really give any explanation what the limitation means.
( https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/scalability/guide_703I21/b_Cisco_Nexus_9000_Series_NX-OS_Verified_Scalability_Guide_703I21.html )
current vlan config on host interface:
switchport trunk native vlan 2990
switchport trunk allowed vlan 10,19,25,121-125,141-152,163-166,168,170-171,173,176,178-179,181,221,224,300,314-316,330,335,360-362,370,380,385,391-394,400,406,426,432,440-441,453-454,4
60-464,468-470,472,818-819,983,996,1321,1326,2100-2114,2300-2309,2500-2503