RE: 802.1Q ARP frame size?

The reason I asked the question was because a switch vendor told me that my
Linux PC should transmit 68-octet 802.1Q ARP frame, instead of 64 octets.
Their switch reduces 64-octet tagged ARP frames to 60-octet when
transmitting out to an untagged port. As a result, the receiving host
dropped the 60-octet ARP frames and communication failed.

I consulted the 802.1Q-1998 standard and it says both 64-octet and 68-octet
802.1Q frames are acceptable.

This looks like a bug of the switch, right?

Thanks,
John