I have now captured a reproducible failure state with substantially more
detail and attached the complete diagnostics.

The important new observation is that the wireless device itself remains
capable of direct scanning while wpa_supplicant is blocked inside the
kernel in:

sock_alloc_send_pskb -> packet_snd -> packet_sendmsg -> __sys_sendto

The blocked fd is an EAPOL (ETH_P_PAE / 0x888e) AF_PACKET socket. Socket
diagnostics show both receive and transmit memory accounting at or
slightly above their configured buffer limits, with packet drops.

Restarting wpa_supplicant removes the blocked process; restarting
NetworkManager afterward restores Wi-Fi without a USB reset, driver
reload, or reboot.

Given this more specific reproduction, could someone from the Ubuntu
kernel networking/wireless team, or an mt76 maintainer, take a look at
the attached traces and advise whether the previously suggested patches
are actually expected to affect this particular failure mode? I am happy
to test a targeted kernel once we know which change is relevant.

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https://bugs.launchpad.net/bugs/2161448

Title:
  mt7921u: USB Wi-Fi enters unrecoverable state after prolonged uptime;
  NetworkManager/supplicant stalls followed by USB disconnect deadlock

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