AuBox AMD 8745HS: how can i update microcode from BIOS to protect from TSA?

Linux Debian 13.4 with kernel 6.19.10 and amd64-microcode package from backports

journalctl -k | grep microcode

Apr 12 20:15:29 somepc kernel: Transient Scheduler Attacks: Vulnerable: No microcode
Apr 12 20:15:29 somepc kernel: microcode: Current revision: 0x0a705206
Apr 12 20:15:29 somepc kernel: microcode: Updated early from: 0x0a705206

Linux packages steel not ready to fix vulnerability. Another way is BIOS update. But no update found on chuwi.com

How can i fix this vulnerability?