Vendor NICs allow for a set amount of mac addresses to be stored as an
allow-list for general address filtering. The exact amount of mac addresses to
be added can be discovered through the ethdev api, but when creating universal,
vendor-agnostic tests for this functionality, some vendors may allow for the
listed amount of addresses not including the device's vendor-given mac address
(so if the device claims it can support 128 addresses, it can actually support
129). Some other vendors take a different approach and allow for the list total
of addresses including the vendor-provided address (so a device that supports
128 addresses can only add 127 extra before throwing an error).

There are ways to avoid this problem from coming up by creating an upper bound
that no device should ever reasonably cross, but it might be best to discuss
what is suitable for testing this functionality in the long-term.