Every NIC, ever made, copies your MAC address onto "padding" on every single layer two datagram ever sent.
There is NO EXCEPTION to this rule.
Around 2002, NMAP enabled users to spoof that MAC address, and this prompted FCC to demand a second UID to be encoded into every NIC made after that.
The UID is part of the firmware, and it cannot be removed or altered.
Every packet sent, either has your MAC address, or after 2002, your UID on to it.
As well as this, there is a two bit field, that are the GCSB and NSA checkbits, and every packet ever sent, gets copied, and relayed to these two agencies.
Remember when "Corona" got shut down?
Bude sent a distress signal?
This is because they lost access to the data stream, and now it only goes to the whitehats.
But make no mistake, every packet you have ever sent, ends up on some agency hard drive.