Update: likely trigger found. A switch-port mirror of an affected Mac caught a panic. The Mac was idle, with no SMB traffic for about 10 minutes. The last frames it received, about 1 second before its link dropped, were a burst of about 60 mDNS packets in 25 ms from a Windows 11 PC on the same MTU 9000 network, many of them jumbo-sized (up to 4468 bytes). They came from Windows Delivery Optimization local peer discovery (_dosvc._tcp.local), which seemed to be stuck in a name-conflict loop. Across about 24 hours of capture, every panic lined up with mDNS traffic from that PC, and when it went quiet for 5½ hours, nothing panicked. The Macs still need an active SMB session to panic, so the mDNS traffic seems to be the trigger and the SMB session the precondition. Mitigation: on the Windows PC, set Delivery Optimization to Simple mode (DODownloadMode = 99 under HKLM\SOFTWARE\Policies\Microsoft\Windows\DeliveryOptimization), which stopped the announcements. We're watching to confirm the panics stop. Details added to FB24912731. If you're seeing this panic on a jumbo-frame network with Windows 10/11 PCs on it, this is worth checking.