Ah I think I know what’s going on: “Predictable” network interface names.
Please try the following:
grep 'net.ifnames=0' /boot/cmdline.txt || sed -i '/root=/s/$/ net.ifnames=0/' /boot/cmdline.txt
reboot
On new images this is done already but on older it may not be present yet and with Bullseye systemd started to ignore an older solution.